I agree with you that "all lives matter" but there is the fact that not just the history behind the issue but location also plays a part. I can think of several locations where I live where spray-painting that would be extremely provocative. Just like the Goulston Street graffito when religious tensions were high in London there are times and places where words can cause enormous potential damage.
Hm.. It can be considered as provocative by people who are not open minded. If you are a radical thinker, you may find a reason to hate.. I used to live in a "ghetto" near Baltimore, and I can say that I have not been so well received anywhere else.
The fact that I am white and from a country that most of the persons who were living in this community have not heard of, didn't give anyone reason to hurt me. :)
You missed that time last August I got a bunch of downvotes from a user because I wrote that the poll tax against African Americans after the American civil war was wrong. Those downvotes weren't because of that opinion. It's because as a caucasian I don't have the right to have an opinion about that part of history.
It's weird when someone complains about how their race gives them a disadvantage to someone who is disabled. I doubt he'd trade my Aniridia and cataract for his skin color thinking that it would make his life better. He was probably too busy downvoting to ponder that for very long.😀