I haven't really encountered that, so I guess my experience is different. To me, saying "black" or "white" women is too broad, because characteristics are individual, but also, things like: where you live, how you grew up etc. do have an impact on how you might act. Example: you grow up in a neighbourhood/culture where men are aggressive, maybe you're more aggressive in order to be able to defend yourself around them.
My parents are from two different countries in Europe...and although the cultures are somewhat similar, the dynamics of how women, in general, act are very different. Bulgarian women are seen as more aggressive/progressive while Macedonian women are seen as more submissive and traditional. They're both European, white, Balkan cultures, but there are still differences. Then, within that grouping, you have Bulgarian women from the countryside vs city women - and there are differences there too (and lastly, individual differences, of course).
I understand that she has that disclaimer and people do judge based on their personal experiences, which is understandable, but I never understood not giving someone a chance just because they "might be like this or that" - cause you never really know until you put your experiences/pre-judgement aside and just try to deconstruct that particular person without letting outside factors get in the mix.