No, I heard Warhammer makes you crazy, and constantly buy expensive miniatures alternately dreading or hoping a new Codex will drop to fundamentally alter the balance of your faction.
But it's like this: if I'm a consumer, and I buy a game, I expect it's rules to either work or to be given errata if they don't. What I don't expect is to be told "refer to a decades old book that is no longer in print" (or worse, in the case of AD&D, wasn't even published by the same company).
If you want a rule to exist in your game, print it in the newest edition.
I think most people would agree with you in the year 2000. I think WotC certainly did. I also think that 3e is a very, very clear example that (a) that expectation is actually very unreasonable for a TTRPG, and (b) they've never done it again since.
Like you can't sit down and write
complete and comprehensive rules to D&D because D&D isn't a closed or isolated system like most tabletop and video games are. That doesn't work for TTRPGs because the totality of game actions you're allowed to take can't be imagined by the author, let alone listed in the book. There's no action for using pitons to seal a door shut, but you can do it. You can do it in essentially every TTRPG system, and I would be very surprised if any of them list it. Even those that still value comprehensive rules like Pathfinder 2e don't, though it does go out of it's way to tell you what a piton is and how to use it, and how doors work, and exactly how to open a stuck door in eye-bleeding detail. The rules systems for RPGs are an
open system. And by being open systems, you can never get a comprehensive set of rules that covers all conceivable interactions. There is no book of rules that will simulate a holodeck for you, and expecting the game to be like that is unreasonable to the point of being ridiculous.
Like look at OP's question. It's not directly answered by 5e at all. There is
no answer. You could read every word in ever D&D book printed since 2014 and you would not get a direct answer. I don't think you'd even get an information to help you answer it. Does that mean you need to stop play
permanently until Jeremy Crawford resolves the issue? No, obviously not. That's stupid.
So someone says, "Hey, it used to work like this in the past." It's neither incompatible nor contradictory. Why is using that wrong? What's valid about dismissing it because it's old and not because it doesn't work?
Now that having been said, if an individual DM wants to mix and match rules, that's their prerogative, I'm simply saying you shouldn't have to do so.
I have never said that anybody
has to do anything. The closest I got to that was saying that fluff shouldn't be considered secondary to hard mechanics.
I'm saying it's not
less of a rule just because it hasn't been reprinted. It's only less of a rule if it's
incompatible in some way. There is
no inherent reason to discard a rule just because it's old.
We accept that
all rules are optional in D&D, right? I don't think you can arrive at any other conclusion from all the parts where they repeatedly tell you to add, alter, transform, or remove whatever material you want for whatever purpose. The game is fundamentally, foundationally,
non-prescriptive with the rules. Doesn't it naturally follow that every rule is still available for use? The only blocker is that it be compatible and not contradict another rule you'd rather use instead.
So if you're playing the game and you run into a temporal problem with a spell and the 5e rules just have
no answer for it... doesn't it make sense to just use the rule you know from a prior edition if it's informative? It's very likely to be compatible even at deep lore levels. It's probably still valid and they just haven't printed it again. Especially if the rule is mostly lore, which is even
less likely to change?
The whole point is, "That's an old rule we can't use it," is not good logic. It turns to pretty questionable logic when the old rules solve problems the current game doesn't. And it gets to be pretty
bad logic when the older rule doesn't contradict anything. I do think that if you're in a situation where the current game is mute and you know the old rule and there's no incompatibility, then ignoring it just becausee it's old certainly feels very incorrect.
And assuming every absent rule functions as it did in previous editions can quickly lead to madness. Do Conjuration spells avoid magic resistance and legendary resistance because they conjure "real" things as opposed to "energy drawn from other planes"?
What? Why is that madness?
Like the rule is
not that conjuration/summoning spells never grant saving throws. Grease, glitterdust, flame arrow, stinking cloud, prismatic spray, et al all did that. The rule is that
magic resistance doesn't apply. In 5e, that would just mean
you don't get advantage on the saving throw. I don't think it affects legendary resistance at all, since that doesn't care about whether an effect is magical or not.
Further, the game absolutely still has the idea that magic can create non-magical effects that can get around explicit protections against magic. I see no reason to dismiss this as the lore reason for why a conjure elementaled ice mephit's frost breath dodges magic resistance, even if we use legacy 5e definitions of magic resistance.
Why can't you use this rule? Because the game is different if you don't? Is that what you think I'm arguing? That adding rules to the game doesn't change it?
Can I still assume magic armor adds to saving throws, as per the 2e PHB, page 102?
I dunno. Ask your DM what rules you're using.
I mean, from my memory the bonus to saves essentially never came up. There just aren't many spells that wouldn't bypass armor. Ice storm, I suppose? That silly ranger conjure barrage spell? For the most part, though, spells that don't bypass armor tend to use spell attacks instead of saving throws. I'm not sure this rule is entirely compatible, but at the same time I don't see why it doesn't work.
Do you not ask your DM how your magic items work?
Perhaps I can still make called shots by taking a -4 penalty to hit and worsening my initiative by 1.
Or that my Gnome has ultravision.
Or that 25% of all magical swords found are sentient.
Or that Dwarves and Halflings cannot be Wizards.
The first one assumes d10 for initiative, making it incompatible as-written. The last one directly contradicts the current rule that any race can choose any class.
But you could change the first one to -2 init, and introduce a gnome race with ultravision, and roll for sentience on 25% of swords, and re-introduce racial class restrictions. I don't even see why the last one is odd. 5e still has racial restrictions, after all. Even after eliminating the subclass ones, there are still items and feats.
Do you think I'm arguing that your table doesn't have to collectively decide what rules to use? That you can just pull out the 1e PHB and claim you can sweep attack as a 5th level Fighter for 5 attacks? Although, I'm not sure that would really do anything; nothing has less than 1 HD anymore.