Leaving aside whether it “has worked” in the past, it’s really hard to make it work now. As Capsian Kang notes, “a program that was designed for a racially binary America never got meaningfully updated for today’s multiracial democracy.”
In 1970, about 95% of the country identified as either Black or non-Hispanic White. By 2020, that’s down to 70%. We went from about 10 million people identifying as Hispanic or Asian to 82 million people over that time frame.
That vastly complicates the calculus of affirmative action, and makes it harder to cast as a reparative program to compensate for past governmental prejudice in the form of slavery and Jim Crow laws.