Having monster stats be "atomic" (as they mostly are in AD&D) rather than "relational" (as they mostly are in 4e D&D) has nothing to with whether or not the game world has an "objective" existence. The hobgoblin phalanxes in my 4e game, marching in formation and maintaining discipline even as paragon heroes cut their way through their ranks, were as verisimilitudinous as anyone's 15th level D&D game is going to get.A proper combat system should be able to produce this effect without changing the monster stats, but simply having the stats of the monsters and the stats of the levelling PCs calibrated so that the relative power difference will emerge.
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I want the game world that seems to have an objective existence and I want rules that reflect that.
As to what counts as a "proper" combat system, I don't know of any RPG or wargame that meets your criteria for that. AD&D certainly doesn't - it uses a special rule for fighter attacks-per-round vs less than 1 HD foes (this is just like a minion rule, except it changes the PC stat block rather than the NPC/creature stat block); and it uses Spells & Swords or Battle System or similar for mass combat.
3E doesn't: the "peasant rail gun" is just one illustration of the point. And as far as I understand it, 5e permits the "peasant rail gun" also.