The next time someone says 'all lives matter,' show them these 5 paragraphs
The real issue is that, while strictly true, "All Lives Matter" is a tone-deaf slogan that distracts from the real problems black people in America face.
The best explanation we've seen so far comes from Reddit, of all places. Last year, in an "Explain Like I'm 5" thread, user GeekAesthete explained, clearly and succinctly, why changing #BlackLivesMatter to #AllLivesMatter is an act of erasure that makes lots of people cringe.
Excerpt
The problem is that the statement "I should get my fair share" had an implicit "too" at the end: "I should get my fair share, too, just like everyone else." But your dad's response treated your statement as though you meant "only I should get my fair share", which clearly was not your intention. As a result, his statement that "everyone should get their fair share," while true, only served to ignore the problem you were trying to point out.