First of all, I want to say I'm sorry that I'm not quite taking this topic seriously. I am saying it. I don't really feel sorry, 'cause it's actually kinda fun, but I'm guessing it's the polite thing to say, anyway.
Sorry about that.
Let me have another go.
In 3E big dragons can have natural armour bonuses of +30 or more. Suppose we relabelled them as "level adjustment" bonuses - would 3E become, in actual play, any less simulationist?
It wouldn't be meaningfully less susceptible to rules-as-laws-of-physics, no (since my point wasn't that it was simulationist, but that it presented rules in such a way that it might seem natural to use them to define the fiction: rules-as-laws-of-physics). It might mess with Touch AC, depending on how it was defined, too...
My contention is no, it wouldn't, because natural armour doesn't actually mean anything in the fiction.
It means the critter is harder to hit with attacks that target AC (like fighters - I mean swords), but not any harder to hit with Touch attacks. Not any harder to hit with Vampiric Touch means something in the fiction. 'Ouch' or 'Ahhhh' depending on which side of the spell formulae you're on.
That's the point of my reference to 4e. In 4e, monsters have a level adjustment bonus to AC.
They /just/ had an AC. It wasn't broken down into components so you could strip it down to Touch AC, Flat-footed AC, Shieldless AC, Non-Corporeal-Touch-Attack-AC, Flat-Footed-Shieldless-Non-Corporeal-Touch-AC, etc...
Which, yeah, maybe a little bit less prone to rules-as-laws-of-physics. Maybe. It is pretty arbitrary.
Suppose we relabelled that as a "natural armour" bonus? Would that make 4e into a more simulationist game? Again, I don't see how it would.
Just re-labeling all of it's AC from AC to Natural AC, no, I don't see it, either. Breaking it down so certain attacks would be much more likely to hit than others - to and past the point of overwhelming the randomness of the d20, though, that could do it.
You're treating the characters as though they are fictional characters in a story, rather than real people in a real world.
It's treating the PCs as though they were PCs in an RPG.
Because that's exactly what they are.
Real people, even in a fantasy world where the gods are real, wouldn't have to deal with the shenanigans of a malevolent outsider bent on making their lives interesting.
Unless there was a malevolent outsider bent on doing so. Which, in could well be the case. The DM & Players could even literally /be/ those entities. In the every creative act creates a quantum reality trope. Or if the DM said so. It's his setting, afterall.