BLM:  Its focus started based on race.

"...A youtu.be a-hol3 is absolutely no reflection on me or you because of the color of skin...."

A white supremacist group is a reflection on me because I'm white.  A natural generalization can happen with some, grouping me in with them.  That's one reason I take issue with their "cause", among others.

Different "cultures" most certainly exist in the U.S., largely grouped around race.  To deny that is being closed minded.  To accept it allows one within that culture to leverage that association and make that culture better.