You would be hard pressed to find anyone who protested over the summer that has had any contact with or knows anything about or even donated money to the BLM non-profit or even cares what they have on their website. It's a catchy phrase that captures the essence of what many people were protesting and not much more. Personally, I gave money to the naacp.
I'm tempted to agree with you because the BLM non-profit seems to be an extremist political organization, and most people are not extremists. On the other hand, that does not explain why so many of those selfsame people become very defensive when you criticize the BLM non-profit organization.