> could you imagine how such people would feel if they were part of one of the out-groups instead and didn't just get lumped together but also had been attacked by the centuries of racism in the US?

You do realize that the majority of white cis heterosexual people live outside the USA right? This is often a source of frustration for me, as people in the USA don't seem to realize the rest of the world exists. All of these things about whiteness, white cishet and white supremacy don't really translate well outside of that context.