I think it does an awful lot. I'm glad you have no issue with it but why on Earth would it cause division? I mean it's not like having a red hot poker shoved up your arse!
Now if the slogan had been "ONLY Black Lives Matter" I'd agree with you totally. Just like if the slogan had been "ONLY White Lives Matter". So, all in all, it's a very worthwhile campaign, I'm sure you'd agree.