A year and a half ago I couldn't either, and was pretty vocal in my dissent wrt BLM here on gaf and elsewhere. Counter productive, I cried. Counter productive, counter productive, counter productive! I caught a lot of flak for that but didn't care because when I think I'm right I can be a little self righteous and stubborn.
But since then we've seen the movement mentioned and discussed endlessly by the media. We've had BLM become a theme at the DNC. We've had the next POTUS and other politicians make it central to their narrative and their platform and none of this would have happened were it not for people blocking bridges, creating frustration, drawing ire and using the attention that all this garnered to give voice to the opposition of racial injustice.
So my stance now is to stfu, because I clearly didn't know shit then and what I think I know now tells me sometimes a lot of people getting frustrated is a good motivator for change.
More power to'em.