When I'm engaged in a debate, there are several markers I'm looking for to determine whether I'm debating a matter of reason or a matter of faith. If I'm debating a matter of faith, there is no point in debating, because faith beliefs are based on personal experience and only personal experience can change those beliefs.
The paradigm of play in the original game was: " If the system doesn't specifically forbid something, then it is possible."
Great. It's been a while since I engaged with the text, but maybe the text actually explicitly said that. But that in no fashion whatsoever engages my complaint. I didn't say that this was a problem caused by hidebound unimaginative players, or DMs making false assumptions about the paradigm of play that they should use. The problem isn't caused by DMs just saying no. The problem is inherent in not having provision for creativity within the rules, and it will effect every group, and in particular it will effect every inexperienced group in a particularly strong way. And to the extent that some DM out there smithed out solutions to the limits of the rules through house rules or rulings, if that was actually a solution then that table was no longer playing "Moldvay Basic" and was likely playing a game unrecognizable to other groups ostensibly playing by the same rules.
If this were not the case then OD&D play would be practically impossible.
Cow patties. OD&D play was developed from wargaming by wargamers. The OD&D game and the later related BECMI and 1e AD&D games were built within that framework and described a game that was largely engaged through wargame rules. Those game rules were sufficient for the early years of the game, when the very act of going down into a dungeon, killing some goblins, and taking some loot was in and of itself novel. You can play that game just fine, and none of the player empowerment issues even gets touched on because playing a 'man-at-arms' is novel in and of itself.
But it's equally obvious that no one was satisfied with that game for very long. Those rules like rangers, druids, and thieves were added to the game at the demand of players who wanted new and novel experiences that they could not get through the existing rules. If in fact prior to codification, "anything not forbidden by the rules" was in fact actually possible, there would have been no demand for rules extension. But as a point of fact, nothing that is not codified in some way is actually possible. Every act you are thinking of as "creative" actually involves codification. Rulings are codification. If some creative OD&D player proposes to strip off his boots and armor in order to become more stealthy, then the DM has to resolve that proposition in some fashion, and however the DM resolves it becomes a house rule (even if it is never written down!) because part of that tables expectations of play becomes, "Naked guys are stealthier." That is codification! The problem is, 99.99% of 'old school' tables never would have had the "Naked guys are stealthier" rule, nor would it have ever been proposed no matter how creative the players because it would have been very obvious that being naked had concrete down sides while being stealthy had no obvious upside.
As rules were added to the game and more codification took place, there was a paradigm shift to the opposite spectrum: " If the system doesn't specifically cover something then it is forbidden". That shift in the approach, especially by newer gamers who never knew any other way, did more to kill creativity than anything else.
This may have happened at some tables. But this is not my experience nor is it obvious why such a paradigm shift should happen. It's not like later editions started including the text, "Anything not covered in the rules isn't permitted." In fact, I'm fairly sure such a paradigm shift did not happen, at least not very early on, because it doesn't correspond to my experience of play through the 80's or the 90's that people were by and large playing very different than they did "back in the day" (granted, I wasn't playing in 1976, but I am familiar with the artifacts of play in that era and people who did). I don't know what evidence you have for some widespread change in paradigm, but in my experience that paradigm shift is associated with players who came to table top from video games as video games became more and more people's first (and lengthy) introduction to role-playing. I've never seen an association between codification of the rules and lack of creativity, except in rule sets that define all valid propositions of play in terms of a limited set of declared valid propositions of play. (That is, regardless of how creative your proposition, mechanically it is represented from a limited set of valid propositions and all the verbage is just window dressing.) Not even 3e did this, and its even questionable that 4e - which went hardest in this direction - actually did that. Again, maybe some 4e DMs did in fact adopt standards of, "whatever is not permitted is forbidden", but if they did, it wasn't because the rules are codified but because of their own gaming background. Plenty of 4e DMs did not fall into that trap.
But perhaps more to the point, "whatever is not forbidden is permitted" is so vague as to be meaningless horse hockey. Falling back to that group that discovered a rule, "Naked guys are stealthier", the same creativity could be used to plea that "Naked guys are dodgier.", yet this application of creativity probably never resulted in any table adopting the house rule that you gained 4 AC for taking your armor off even if the rules did not actually forbid that. And to the extent that there were tables out there that had gotten that creative, they were certainly playing Moldvay Basic only in the kernel, as the prenumbra of rulings around that kernel that had been codified had become vastly more important than the game itself. And this only happens when in fact those rulings are codified. The truth of the matter is that it has nothing to do with what a game forbids or permits, what really matters is what the rules encourage and how they empower the participants to make decisions.
Before there was a thief class, being sneaky was still a part of the game.
Sure, but before there was a thief class, there was no way for a player to empower his character as especially sneaky. And at no point could a player validate inside the game as opposed to in the metagame that his stealth had some predictable chance of success. Sure, maybe and rarely some group said, "We put out all our torches, take off all our armor, take off our boots, and stealthily sneak up on the beast.", and maybe and even more rarely some OD&D DM thought to himself, "That's cool and creative. What should I do about that.... Let's give them an automatic round of surprise!", and maybe even more rarely that OD&D didn't regret that decision because his game was taken over by naked dwarves with battle axes and players with the expectation that "If I take off my armor and boots, all things being equal, I should get to attack first." But I first argue that before the thief came around that isn't actually the way most groups played, and even if it was no one had a way to say that they were more stealthy than anyone else.
If being stealthy were "impossible" due to there being no rules for it, no adventurer would have ever seen 2nd level.
Cow patties. Other than not making "excessive noise" and thus ruining the chance for surprise, the vast majority of tables did not play that way. There is no artifact of play suggesting that that was the way the game was normally played. Gygax's table doesn't seem to have played that way. All the artifacts of play from that era suggest the vast majority of tables approached the game through there background, which was as tactical wargamers. So what you would actually see is war dogs, hirelings, torch bearers, and the application of weapons and terrain to achieve tactical advantage - all the things that became codified in the early rules of the game and which were called out as important to play. There is nothing suggesting that beyond the most perfunctory, "We try not to make a lot of noise", that stealth was a huge portion of play.
Therefore, regardless of the absence of formal rules, the game allowed something that, while not defined, was not forbidden.
So? That doesn't mean it empowered the players.
Even if something isn't forbidden and even if the game says do whatever you imagine, if it is not called out as possible and if it is not validated as the way to play, it's almost certainly not going to happen. If a new player playing OD&D kits out his fighting man with sword and shield, and he sees the hobgoblin and says, "Ok, now I want to stab that thing with my sword, how do I do that?", he's going to get immediate positive feedback and basically every table he plays at. The DM will say something like, "Well, roll a 20 sided dice to see if you hit...", without any hesitation. But if that same player says, "Ok, now I want to run over and grab that thing in a bear hug...", at 99.9% of the tables he's going to get immediate negative feedback on multiple levels. Experienced players are going to give body language or possibly verbal rebukes. The DM is going to hesitate as he tries to figure out how that should work, and quite likely even if the DM doesn't say "No", he's going to punish the player for it because it doesn't feel write. Creativity over, with nothing that the player can read to recover the idea that, yes, in some situations that might work, and here are some guidelines.
Again, it doesn't matter (or rather it doesn't only matter) what the rules forbid or permit (if the rules even have that concept). What matters is what the rules validate as a procedure of play, and provide a resolution for of some sort. What they are silent on, isn't normally a part of the game, even if your players are creative enough to regularly place in major tournaments at major gaming conventions.
Perhaps your players were not that creative?
This is one of several reasons I don't think I'm in a reasoned debate and that I'm arguing with an article of faith. Because, one of the first things you leap to is an ad homin attack to defend your position. If that is the substance of your argument, it isn't a very strong argument.
The game was written as a way to unlock YOUR (the player's) imagination. D&D isn't much good at doing that if your imagination is limited to that which the authors have already imagined. The system being silent on some matters isn't stifling creativity, it is encouraging it. If the system isn't saying no, then it is saying possibly yes.
This argument is self-evidently nonsense. Yes, it is true that the game was written with the expectation of unlocking the player's imagination. But how in the world does that translate to the less rules you have, the more your imagination is unlocked? If that was true, not having the game at all would create the most imagination in the players. The very fact that the game 'unlocks the imagination' disproves the thrust of your argument in the first place. The game caused the readers to think of things that they wouldn't have thought on their own. But by and large it is the expectation that what those game readers read was mostly what they were inspired to think about. That is, mostly they used the tools that the game gave them, whether spells, or subsystems, or monsters, or tables, or what not. By and large most of the things built with the game were made with the elements of the game. That doesn't imply that the players weren't being creative, any more than a person who plays with lego bricks or minecraft isn't being creative just because they are using what they have at hand.
But what it does mean is that all those supplements, magazine articles, modules, and settings were eagerly consumed because each of them expanded the imagination of the players, and provided new vistas for looking at the game that wouldn't have been seen without them. Your arguments boils down to, "Now that I have more options, I feel disempowered."
Not my experience at all. The silence on certain matters is what opens up creativity. One has little need to be creative when detailed procedures for everything are all laid out and ready to follow. Necessity is the mother of invention.
The second reason this debate doesn't feel like a debate is I'm the only one not speaking in generalities. Faced with the challenge that your 'old school' game probably didn't have duelists and sumo wrestlers in it before someone codified that, you breezed on to generalities without even conceding that probably was the case. Not even a shred of counter evidence for that was provided. No attempt to explain how, that might not be true, but at your table someone was allowed to play R2D2 or how that worked, or anything else of the sort.
I disagree that Moldvay basic is silent on how to explore the game world. Reading the example of play included gives a fair bit of insight into how play takes place. The DM describes the environment and the players interact with it. As exploration takes place, the DM answers queries, and based on that feedback the players make decisions or ask further questions. Not exactly something that takes hundreds of pages to explain.
On the contrary, the very fact that it takes literally hundreds of pages to explain is the reason most early games didn't even make the attempt to explain it.
Besides which, it's clear I'm talking right past you. What you described was a procedure of play, and what is basically D&D's default procedure of play from the 1970's to the present day. But that in no way describes how to explore the world. It leaves it up to the DM to invent the means of doing that, because the portion of the procedure of play that is notably missing from that is the resolution itself. How do you resolve interaction with the environment? If I decide that I'm going to use my axe to bash way the stone frame of door, what happens? The game is silent on that, leaving it up to the individual tables to decide. What's perfectly clear is that with no resolution for that, even in the OD&D world that was supposedly so "creative" that proposition would have been in the vast majority of cases negatively received (even if it was imagined), because it wasn't part of the game presented to the players or which the DM intended to run. I'm sure it was attempted at some point, but it's equally clear that it wasn't validated as good play, creative or not.
If a system doesn't explicitly call out that something is possible, it effectively forbids it. All that codification occurred to empower players.