It's not just that it's an inconvenient hypothesis, it's that it's an hypothesis we've already been trying for several hundreds of years. It's how we justified slavery, the holocaust, colonialization. These people weren't dumb, they genuinely believe black people were inferior, so they would therefore have the best quality of life by being slaves. You see, we're really helping them by taking them from their backwater countries of tribal war and giving them opportunities to do structured labor that their feeble minds could handle.
Time and time again, we prove those hypothesis wrong. As countries develop and equality is prioritized, we see more and more differences disappear.
Ultimately, I have no reason to believe we have achieved the apex of development or equality. Systemic racism is real, because racism doesn't just disappear. We implemented integration just a few decades ago in a lot of communities, and that disconnect and resentment that built doesn't just - poof! - disappear. It continues on and manifests in less opportunities for education, more drugs in communities, and a lot of second order effects that transcend generations.
We even still see black populations today distributed as we saw them during slavery. And that was 150 years ago. These things don't get solved, they just get better, a little bit at a time over very long periods of time.
I dismiss the hypothesis because we have already dismissed the hypothesis more times than we can count. And, I have no reason to believe this time it's different.