Ta-Nehisi Coates, on "Why 'Accidental Racist' Is Actually Just Racist".
The assumption that there is no real difference among black people is exactly what racism is. Our differences, our right to our individuality, is what makes us human. The point of racism is to rob black people of that right. It would be no different than me assuming that Rachel Weisz must necessarily have something to say about black-Jewish relations, or me assuming that Paisley must know something about barbecue because he's Southern.
It is no different than the only black kid in class being asked to explain "race" to white people, or asking the same question of the sole black dude in your office. The entire fight is to get white people to respect the fact that Mos Def holding a microphone is not LL Cool J holding a microphone, that Trayvon Martin is not De'Marquise Elkins, that wearing a hoodie and being black does not make you the same as every other person wearing a hoodie and being black.