It follows logically from affirmative action. If 60 years of affirmative action haven’t fixed the problem, then there are only two likely reasons:
A) there is a vast conspiracy by whites to keep black people down, which can only be stopped by the elimination of the white race, or
B) there is a statistically large difference in ability between whites and blacks, which is genetic in origin, and cannot be fixed.
Only one of these possibilities is acceptable to the left.
I think there is another very likely reason. Affirmative action helps some people, but really just becomes a way for elites to maintain control by selectively conferring benefits on some people.
Improving education, promoting positive family values, and encouraging small businesses and independence among poor communities would have worked much better. But success for African Americans is not what the liberals wanted. They wanted dependency and control.