I somewhat agree with what you're saying, but I cannot fully agree 100% in all cases.
For example, if a video game world is set in Japan or Poland, I still don't think it makes sense for all the protaganists to be black. That would just be too far reaching and completely unrealistic, even for "one person".
I have never been to Poland, but I have visited Japan on a two-week trip about ten years ago. And we hit all the major cities (Tokyo, Osaka, Kyoto, Hiroshima) along with plenty of smaller towns in between.
As you may know, Japan is a heavily public transportation country (walking, subway, rail, bullet-trains, etc). So I must have easily passed by hundreds of thousands of people during this trip. I seriously do not recall a single native black person the entire time (by native, meaning not a tourist and not a US military member).
If there were, it certainly was not more than like 1 or 2 or 3.
So no, it would not make sense to me to have black protaganists for any video game completely set in Japan. I've heard similar percentage demographics for Poland, although I have not been there myself.
Now if you're strictly referring to settings in America, then that makes a lot more sense.