I don't agree that "a real choice being offered is impinged upon in direct proportion to the degree to which the optimal choice is clear to the players", because it presupposes that there is an optimal choice.
Okay, let's talk about choices for a second.
(1) In order for a choice to be meaningful, the result of a given option cannot be the same as that of all other possible options.
If I say "Choose a number between 1 and 6", but the result is the same regardless of what you choose, then there is no real choice. This is the problem I have with "Regardless of whether the PCs go left or right, the same thing is waiting for them" GMing.
(2) Assuming any goal, whether GM-presented or player-driven, if the result of an option moves the PCs forward toward that goal, it is (in general) a better option than one that does not. Likewise, if resources are to be taken into account, an option that reduces expenditure whil moving toward a goal is (in general) superior to one that includes heavy resource attrition.
(3) Since we are discussing the results of meaningful choices, there must be both context (sufficient information to at least make the choice something other than the result of random chance) and sufficient consequence (i.e., all choices cannot be equally optimal based upon the goals of the players, whether self-generated or GM-generated) to make the choice meaningful.
A choice where no option is more optimal than any other is, essentially, meaningless. Counter-examples always, perforce, contain some element of optimization, even if what is optimal is the level of fun the participants enjoy.
For example, if you say
The point of interesting NPCs, for example, is not that optimal choices are obscured, but that interacting with them will give rise to multiple courses of action that are viable and exciting relative to the game me and my players want to play.
I would point out that those multiple courses of action allow for choices that optimize what game you and your players want to play (i.e., they allow the players to drive the game in a direction they find more enjoyable), and the excitement arises from the tension between what is known and unknown while driving the game in that direction.
For example, you say
Once the players know that the barkeep is a cultist, what is the optimal choice for them to make? There isn't one.
But, then, your next sentence demonstrates that, in fact, there is one.
How they respond depends on where they want the game, and the story of their PCs, to go.
"Optimal choice" =/= "mechanically optimal choice" of necessity (although, of course, it does in some contexts).
The same problem lies at the root of your other examples. You are not describing cases where there is no optimal choice, you are describing cases where there is insufficient information (specifically, the desires of the player in question; i.e., that player's interest that makes one option better than another) to know the optimal choice.
It does not follow that, because you and I see different choices as optimal, there is no optimal choice. Nor does it follow that, because you and I would choose differently under conditions where consequences are obscured, that we would discover that we had made the "best" choice for our desires.
Given my initial premise (that "a real choice being offered is impinged upon in direct proportion to the degree to which the optimal choice is clear to the players"), it seems somewhat odd to me that you would attempt to refute that by demonstrating real choices where the optimal choice is even more obscure!
Or, perhaps, another way of putting it might be
From the ingame point of view, some choices are obviously more optimal than others relative to a given set of PC goals, but the whole point of the example is that the choices invovle, to an extent at least, setting the PC's goals.
which seems perfectly consistent with what I was saying, to me!
Moreover, the part of my post that you didn't get (about the statue) seems in conflict with this idea. Knowing that the players are not going to find a statue, or a barkeep, interesting presupposes that you
can predetermine an optimal choice, as well as predetermine what the players will find interesting -- and the barkeep isn't it!
(Ditto the statue, etc., in the examples you didn't get.)
So evil cultists make interesting NPCs (they can be killed, bargained with, converted, or gain converts, all of which have exciting implications for a game in which multiple PCs are priests or paladins, even the non-clergy PCs have strong religious commitments, and this is not just because the players wanted a PC with healing but because they enjoy exploring the mythic/religious dimension of the gameworld and of game play). Barkeeps, as a general rule, do not.
Thus if I mention a barkeep to my players they are likely to infer that s/he is an evil cultist, or otherwise of potential interest to them.
Yes, they would.
Whether or not you find it problematical, this is exactly what I described upthread. If you only mention the things you believe to be important, the players automatically assume (1) that anything mentioned is important, and (2) that anything not mentioned is not important.
Thus, you say
See, my preferred solution to this particular conundrum is to assign the Wolf-in-Sheep's Clothing a Stealth score, and to only mention it under one of two conditions: a PC succeeds on a perception check, in which case I mention that they notice a carnivorous plant disguised as a rabbit on a stump; or no PC succeeds on a percpetion check, at least one PC comes within range of the monster, and I mention that the PC is a victim of a surprise round from a carnivorous plant disguised as a rabbit on a stump.
which is, of course, a perfectly valid way to play, but one which (to some degree at least) minimizes player choices because the PCs never have a "full view" of their environment.
And, yes, I do understand that there are benefits to this approach. For one, you do not need to worry about the players going off on a tangent, simply because no tangents are presented.
Furthermore, as a GM, I couldn't predetermine an optimal choice because the range of options isn't known to me.
But it could be, if you decided that you were the sort of GM who wanted to lead the players by the nose. It is easy enough to do. All you have to do is decide what the players
should choose aforehand, and make ever other potential choice result in maximum suckage.
(And, yes, games like that do exist.....and arguably, some design paradigms lead potential GMs in this direction more than others.)
It is well within the power of the GM to constrain player options. In fact, by limiting what you describe of the world, you perforce constrain player options. And, as no GM can possibly describe everything that the PCs would see/hear/smell/feel, to varying degrees we all constrain player options by the choices we make when offering descriptions of the world.
Some simply constrain these options more than others, for good or for ill (or, as seems more likely the case, to offer a composite of good and ill that seems interesting to that particular GM).
AFAICT, you are replying to the suggestion that "a real choice being offered is impinged upon in direct proportion to the degree to which the optimal choice is clear to the players" by disagreeing with the premise, but basing your disagreement on statements that strongly support the premise: essentially that, in some cases, the optimal choice is so obscured that you do not know what it is, and that these choices are meaningful.
The base statement would be refuted if, instead, you could demonstrate a case where knowing what is optimal somehow results in the choice being more meaningful.
RC