It's a description some wear with pride and some see as a pejorative.
Social justice warrior. They fight for what they know is right.
"Social Justice Warrior" is a term for people who believe a lot in something, used by people who don't believe in anything.
Proof is in asking those selfsame people: well, that's over the top, what's a better method of doing what you feel is right, or addressing issues? 99 times out of 50 you will get the same theme: nothing, nothing needs to be done, there's no issue there, lolgay, feminazi, etc. It's a term used by people who don't want to believe there is any injustice, so they have to deride anyone who does.
But some people clearly take things things over the top, and become far too aggressive or inflammatory, even if their motives are good. Even if their points are good! So what's a good term for those folks?
"Annoying twerp." Or "Geebus have decaf."
You only bother creating a label that attacks an entire group, if you are more interested in spreading a political idea about that group, than you are by the individual person.
It's like when someone says "well geez, you can't help everybody."
I have found that when most people say "you can't help everybody," they are really saying "I don't help anybody."