When BLM first started up and sort of made sense (for that one week before stuff started hitting the fan in full force), when people said "All Lives Matter" in response to them saying "Black Lives Matter", it came off as dismissive. Now, to make the jump from dismissive to racism is entirely up to interpretation. Like I said, before the information came out about Michael Brown, I understood when people got annoyed when someone said All Lives Matter, because it was only in response to Black Lives Matter, which, as I stated earlier, comes off as almost entirely dismissive of the issues they were bringing up. You know, when they were actually bringing up issues and not just stuffting all over their own neighborhoods and calling for the death of whites or w/e.
All Lives Matter began as a counter-slogan or whatever. I would be beyond hesitant to call it, at any point, tribal, because not every little thing that goes against black people is tribal, but it is at the very least dismissive of the issues between black people and the police. Of course, black people aren't the only people who have issues with the police, I'm just explaining the viewpoint behind it.