I think you proved the parent comment's point with this statement by accusing a whole class of people of being guilty of something the vast majority had no part in and would find abhorrent.

It's understandable that they would resent such blanket statements. No one alive today participated in slavery, the vast majority of their ancestors did not participate in it. Many families hadn't even immigrated yet and may have had their own discrimination issues to contend with.

> This is more "both sides are the same" rhetoric that is only used to empower the fringe beliefs and extremism in the American right.

This is exactly the sentiment the parent comment is alluding to. I think the American left is more guilty recently of avoiding introspection and dismissing criticism, to the detriment of advancing their mostly positive goals.