I do quite a bit of Facebook, and while I have never been insulted by a friend, I just watched someone I don't know have a complete - and wildly uncalled for - meltdown over a FB friend's post by interpreting something completely non-political as political. So it certainly does happen on Facebook, not the first time I have seen it.
My problem with Facebook - and easily ignored when I choose to - is the ignorant comments by so many people to news articles that turn up in my feed. It does not seem to matter what an article is about, there are instantly a ton of nasty comments and worse if there is political content. So in that regard, the Boneyard is a relief from that sort of thing; while I admit there is a lot of content on the BY I don't read, I have rarely seen major conflict and political matters are generally kept away. Hooray!!!!
I don't do Twitter, but I have absolutely no objection to it.