Not to get into a GNS derail, but how are people defining "simulationism"? It seems some of us are talking pass each other coz we defined terms differently. Simluationism used to mean genre emulation and just the running of an internally consistent world. Some uses it to mean simulating reality. Others use it more in the sense of running a computer simulation where you plug in the rules and data and the production of whatever results (sensible or otherwise) is its own goal.
Yeah, that's an ongoing issue. There's "GNS Theory" in which 'Simulation
ism' is play style, descriptive of how players approach games more than of games, themselves. Simulation can also, obviously, mean matching mechanics to some yardstick, be it realism or genre emulation. Simulationist D&D can also be a sort of navel-diving exercise in which the game simulates /itself/ as strictly as possible.
I'm not at all convinced that classic D&D was simulationist in any of those senses.
2e was actively sticking to the classic D&D feel, making minimal sort of 'house keeping' changes to the system, so it could be considered a simulation in the last, self-referent sense.
3e is enthusiastically embraced by self-identified adherents to the GNS simulationist style of play.
4e delivers some pretty nice genre-simulation, leaning towards the action-movie/pulp-fiction end of the heroic fantasy spectrum.
5e is being designed as a sort of toolkit which will let you re-invent each of the prior editions, emulating their 'style,' so I guess it's very much the self-referent simulation of D&D sort or of simulation.
So, yeah, it's easy to point to just about any edition of D&D and argue that it is or isn't a simulation or is or isn't 'simulationist.'