I feel like it's incredibly pessimistic and cynical to see that as the purpose of social media. I don't believe that sites like LiveJournal or MySpace (my earliest two recollections of social media) were literally designed for the purpose of letting people get angry and enraged and furious at people who disagree with them. But maybe that's because I saw those sites through the eyes of a much younger person; someone who didn't have the burdens of adulthood and who just wanted to chat with friends and be accepted. I never thought "good, now I can 'anonymously' yell and scream and preach my views and violently lash out at all who disagree". Just as I'm still not doing that. I disagree with what you said, but I haven't shouted, haven't called you any names, and certainly haven't had any violent thoughts. Why? Because I'm a grown ass adult who was raised to know the importance of being civil.
Blaming the platform for the actions of its users just seems silly. Blame the users. Facebook isn't holding a gun to your head and telling you to be a dick to people. They're just choosing to do so for their own reasons.