I am sure you are misreading things, Shane. I’m sure you’ll agree it’s not racist to point out there is racism against black people, even though it involves understanding which people count as “black” according to that racism. Nor is pointing it out dismissing the accomplishments of white people.
What Ashley and Missy were doing is talking about how there is even more racism against people who are regarded as even “more black”, and to understand that problem you have to understand how people are defined as more or less black according to that racism. It doesn’t equate to endorsing that awful division, but just like the white-black divide in general, if you won’t see it you can’t oppose it. Nor is it dismissing the accomplishments of any black people, who after all still face racism regardless.