[FabHK]

> If you require one group of people to score 90 on some test in order to be hired, and another group to score 80, then among successful applicants the second group will have lower average scores than the first.

That's not necessarily so; you could require mice to be heavier than 90 grams, and elephants to be heavier than 80 grams, and still have your elephants be heavier on average.

(I don't want to wade into the bigger argument, just pointing out that "that's simply how statistics work" only under certain conditions (which most likely apply here, but you wrote "there's no getting around that" when there is)).