It’s just social conditioning. If everything you see in the media you consume is positive about whiteness and negative about blackness, then of course some are going to fall prey to that mentality.
Especially if that conditioning is bolstered by social interactions with others. Part of the reason a lotta blks are breaking out of that pattern is because it’s become heavily shamed in our community recently to diss people for skin tone. Also there’s been a larger demand to see a more diverse representation of darker skin tones in the media.
I can show ya’ll magazines growing up vs now and unless it was JET, I rarely saw pictures of beautiful dark skin black women represented in a cherished light with kinky, Afro textured hair. So a lotta people grew up not associating beauty with darkness.
Now, it’s come a looooooong way.
The internet and social media not only had dummies exposing themselves, but it’s also much easier to find beautiful depictions of women with darker tones. So it’s harder to pretend like they don’t exist. If you truly have a preference it’s fine but being willing to overlook someone for skin tone when they legitimately beautiful is mental illness. And social media has made it harder for those types to hide their ignorance.

I’m not dark skin. Just a regular brownie but some of the behavior I’ve seen towards beautiful darker women has been disgusting to me. Always has been.
But also I think we need to do a better job of redirecting our attention to people who aren’t mentally broken instead of crying to change these types.