I always try to give the writer some slack for exaggerating for effect, or generalizing too much to simplify a point, and read between the lines their true argument. So I read the entire article Yes, All White People are Racist, and there was not a single caveat, not a hint at any nuance. Reading that article leads to the conclusion that Barack Obama was raised by a racist mother.
I asked Catherine why she can't add a few adjectives, and she responded that she doesn't have time, although two adjectives - "all", and "every" - permeate hers and Marley's writing. Maybe Black writers are tired of saying "not all White people", which is odd because they rarely say it, but I can assure you that White readers are just as tired of hearing "All White people", or the latest abomination, "Dear White People ....."