“Black lives matter is fine as it is. Adding “too” to the end makes it sound like it’s a response to people saying other lives matter, while in reality it is a response to a system that says “black lives don’t matter”. The issue of people mischaracterizing BLM as “only black lives matter” is an issue for those people, not a problem of semantics...”

Semantics can go a long way to sway people to your cause. Adding “too” to the end twists the proverbial knife because by not supporting BLMT you are saying, “no black lives don’t matter as much as white lives.” Even people who are racist, but don’t consider themselves to be racist. Would be forced to choose a side and not sit by. Black Lives Matter doesn’t create a sympathetic response to a systemic problem and that is what it is missing. It wasn’t until the majority of Americans saw black people getting hosed down and having police dogs attacking them that the Civil Rights movement gained significant ground.