If you were on a forum and said a racist comment like the one in the article, if people didn't like it you would probably be put on blast and have ruined your reputation on that forum as well. Difference is that it's not your face. If you feel like it's okay to say racist things, you probably are not going to realize your mistake unless called out by someone.
So to me it seems like social media is just piggybacking on the proclivity of people's desire to be seen and heard.
This is why social networks in their current form are a lousy way of expressing original thought. Even if you don't say things particularly controversial, if they're not in line with the lowest common denominator, the chance you'll see any legitimate engagement is slim.
Forums, on the other hand, are largely anonymous. You'll definitely be put on blast for what you say, but the inherent anonymity helps to deter the angry crowd from shutting down conversation by default. Of course, it depends on who is running the forum. Reddit, as much of a cesspool as parts of it are, is a modern example of how anonymity leads to far more productive conversation than one may ever see on the likes of Facebook or Twitter. Yes, Reddit shuts down subreddits it doesn't like on occasion, but it's overall more hospitable to an exchange of ideas. Good luck having those same conversations on social media, even if you manage to use a pseudonym.
CGP Grey's take on how outrage is used to exploit us through social media: (Yes, I link this often, because the message is valuable.)
Although, maybe it's too hard to efectively generalize social media usage like that.
Is it possible to design a system that can ONLY be used responsibly? At lease in matters of expression?
Those initiatives weren't designed to lessen the "exploitation of moral emotions", they were designed to give preference towards the extreme moral emotions of a particular world view.