I don't know. I think, perhaps, in the 'real world' we learn to become very good at choosing who we associate with, and don't spend time with 'destructive' people (for lack of a better term), but perhaps this has yet to be learnt properly online.
For myself, I literally have never seen an argument on my Facebook feed. I have about 150 Facebook friends. I don't see flame wars on Twitter; I follow people I find interesting, that's all. I subscribe to subreddits with sane moderation policies. Generally, the internet I encounter on a day-to-day basis is actually quite a civil, friendly place.
I just don't think the online world is that much different from the real world. You choose where to spend your time, who to spend it with, and that shapes the experiences you have–just like the real world. Is it really so different?