Is BLM a distinct organization, where these people were recognized as representatives of the organization? If so then yes, BLM can be held accountable. If it's a distinct organization that didn't recognize these people as official representatives of the organization prior to the incident and continues not to then no, they can't be fairly criticized. If it is not a distinct organization to begin with, then BLM itself doesn't really mean anything in the first place and I don't really see a point even debating it.

My impression is that this is basically another twitter movement, and the problem is that as someone else here said, there's no barrier to entry, no one's stopping anyone from trying to take the reins, regardless of whether or not they make a fair representation of the movement's message.

I've mostly seen the criticism directed toward the BLM organization itself, and not all black people generally. That is probably just happenstance on my part, and I make no claims that it isn't happening.

I'm honestly not paying that much attention to it, but I believe the philosophy of my comment applies to much of reddit, and in fact much of the world, most of the time. Consider how you see people perceive Muslims, Christians, Chinese, Indians, Afghans, and I imagine most groups you can think of. The silent majority is often bundled with the extremist minority, then when some of the silent majority tries to speak up, the people that bundled the two groups together become hateful to those speakers, and some of that silent majority becomes extremist in self-defense against the hate. It's a self-feeding cycle of hatred, and as I said, it is tragic to see that occurring.