Black people are the "original" humans, all other races descend from much smaller groups of humans that moved out of Africa and colonized the rest of the globe (plus some admixture from extant Homo species).
So a bunch of alleles have never left Africa in sufficient quantities to persist in non-Black populations. And this probably applies to ADoS Blacks, too, since their Black ancestors were bought from the same entrepots in Western Africa.
I doubt that any serious racists consider that there is some single "black race".
Nonetheless, as far as I can tell, you're presenting the case that there are significant genetic differences between black races and other races, in which case: why can't some of those alleles code for intelligence, and why can't that result in a difference in average intelligence?
> I doubt that any serious racists consider that there is some single "black race".
Except that HBDers are doing exactly that. Last I checked, Igbo immigrants from Nigeria were doing very well in the British and European education systems. And there's other subcultures in Africa with a historical focus on education, like the Ashanti of Ghana, etc. It's not racial genetics; it's all about culture, norm-setting and equitable access to the education system.
Ghana is also one of the most stable and democratic African nations today, and the Ashanti Empire was renowned for its advanced political administration, so there's that.
There's no reason they can't. People that want to taboo HBD are afraid that the slope from "some difference in socioeconomic outcomes between races is inherent" to "all difference in socioeconomic outcomes between races is inherent" is too slippery, and the only safe way to ensure that the policy changes they want ever happen is to stabilize the consensus around "all difference in socioeconomic outcomes between races is due to systemic racism".
It's trivial to find an African person with more genetic similarity to an Irish person than he has in common with a different African person. Genetic diversity in Africa is massive. Think of the various Pygmy people as just one example.
So a bunch of alleles have never left Africa in sufficient quantities to persist in non-Black populations. And this probably applies to ADoS Blacks, too, since their Black ancestors were bought from the same entrepots in Western Africa.