That just the "magical elf-game" argument again.
Only slightly, and I suspect not in the way you think. My position isn't "fireballs are fantasy, so you aren't simulating something realistic."
There are good reasons why most simulation games take a narrow focus on their domain - the broader the domain gets, the more heavyweight and complicated the mechanics of simulation must be. And for tabletop play, this is humans going stepwise through those mechanics. But RPGs are not limited in domain much at all.
Thus, the weight of mechanics needed to do a solid simulation of an entire fictional world in an RPG (of any genre - like, say, the Bourne movies, which are pretty solidly mundane, not magic elves) is just plain burdensome.
The compromise is typically picking the bits you really want give simulation attention. This is an entirely reasonable choice. But it compromises the sim-dominance in the game.
This doesn't mean the playstyle is "invalid". I have played too many hours of sim-heavy games to think that. It does mean that having this as the primary focus of the activity seems a weird choice that could use explanation.
I like fantasy and science fiction. I also like history. Fantasy RPGs combine these things very effectively, and I'd prefer the parts of those RPGs that correspond to reality to actual model it as closely as is practical.
I have a story I could relate about such, but it is late. Perhaps Ill get to it tomorrow.
For the record, Civilization is my favorite video game of all time. I prefer Civ V.
Civilization is awesome. No argument there.