tl;dw and tl;dr (will rectify later), but:
- would require actual knowledge and research
- would likely induce balancefags whining
- possibly lack of magic
- value dissonance and massive SJW turdalanche it would trigger
From what I've managed to skim the latter 2 have already been mentioned.
Use ancient, medieval or very early history as setting, add in mythological elements, and you got lots of subtle magic and god/gods helping out devout adventurers, so lack of magic is not necessary.
Fuck SJW turdalanche, it's just free publicity for the game when they all rage about how horrible that game is in depicting [insert oppressed group here]. Then again, when you realistically portray the middle ages, for example, women wouldn't be totally "oppressed", there would just be clear gender roles, and yet the player could still play a female character because exceptions existed (there are many stories where a woman took up arms in the defense of her city and this raised the morale of the troops so much they beat back the enemy; they are exceptions, but the player usually IS an exception in any game out there).
Balancefags can go fuck off, too.
Actual knowledge and research would be a problem, but hey, I'd take a job if anyone were offering.