It is not misunderstanding, I simply reject the myopic dichotomy. Yes, I fully get the gameplay reason for including these creatures in the first place. But if we care about simulationism too, then we play them coherently and with integrity.
If I were trying to take up the position that you're taking it would be very difficult for me to use "if we care about simulationism too, then we play them coherently and with integrity" to defend against:
* Well why isn't
this dungeon (D&D jargon stand-in for whatever the place is; ancient ruins, cave, haunted manor, labyrinth, whatever) room stocked with benign furniture or rubble and
that or a refuse pial or privy leavings and rinse/repeat until you get to the 3/15 consequentially stocked dungeon rooms (versus the orthodox-ish proportion of 14 : 1 consequentially stocked - denizens/traps/hazards/secret doors/treasure with strings attached - rooms)?
* Why isn't
that room and
this room and
that other room over there entirely barren (or nearing it enough to be effectively barren)?
* Why is this sequence of rooms stocked and topographically arrayed in such a way that it achieves Encounter Budget x, then y, then z (if you're capable of resolving the conflicts without "raising the alarm") with x, y, and z being specifically curated toward a set difficulty?
* Why is the treasure typically unironically themed to PC archetype?
* Why does the BBEG always have their henchman or Golem or pet dog in their quarters and why is their spellbook and spell loadout always outfitted for effective combat? Why are they never asleep...or without their buddy...or loaded out for various and sundry (like surveilling the next target and cleaning up the joint and entertaining themselves and peering into their future and experimentation to prolong their life)? Why aren't their fingers every exhausted or sprained from prior day's castey-work? Why aren't they suffering from food poisoning (its 2022 and I've suffered from food poisoning 6 times in the last 10 years!)?
* Why is their intel on PC location/capability/mobility practically bulletproof when modern Intelligence Agencies routinely put out briefs that are utter rubbish, partially or wholly detached from reality?
* Why do we never get to the dungeon and HOLY CRAP A CAVE IN BURIED OR A SINKHOLE SWALLOWED THE ENTIRE COMPLEX AND EVERYTHING IS INACCESSIBLE AND SHEER DUMB LUCK ENCURTIANS-INATED OUR BBEG?
The answer to all of these is in large part (of course)
conventions of play +
contrivances of D&D. If we can work around all of the baked-in conventions and contrivances above (and more...those are just surface scratching) to claim
"these aren't really and truly conventions and contrivances necessary to functionally fill out the playing of a 4 hour dungeon crawl...they're (abra kadabra...allakazam...walla wall washington) a coherent simulation with integrity(!)," then why isn't every play ever a simulation? Given how "stranger than fiction" our totally mundane world is, it seems pretty plausible from here that any imagined space of a mythical D&D setting would be filled with possibilities far more infinite than what Earth has on offer (and Earth has a crazy number of possibilities both foreseeable and completely out-of-left-field WTFs-ville). So it seems to me that the threshold for the "not a plausible simulation" test in D&D-land must be so incredibly low that the bar is nearly hugging the ground.
Now I'm sure your answer is "no, I don't agree" (otherwise you wouldn't be where you are in this discussion and in past discussions).
So then I'll ask "how/why is your plausible simulation test where it is(?)" and "why do you feel that bar (the 'reskin the D&D conventions and contrivances to totally legitsville' bar) isn't so low that its trivially surmounted by a crazy number of explanations for any given thing such that the subset of things that = 'coherent simulation with integrity' is nearly infinite?"