I agree with you, but, one thing does not exclude the other. The point is, it is much easier to make a fictional, that can of course be based in real life, without demanding so many details.
Do you wanna Korea? or vietnam? Because let's face it, not many people know how vietnam is.... you just need to put a big city, few coastal towns and the jungle.... with Some mountains... hell, who has not flyed over vietnam caucasus.with the mod?
You can also put some interesting tactical geography, desert and jungle (in south America you can see that, sort of)