Moderation in social media, that is new. But forums which were pretty much the social hotspots before Facebook came out invented moderation of the community. Either way, it could help but might be fought by some.
You are right though about Linkedin, not so much Facebook. Because I have over 200 friends I only know 20 of them. But it is a bit easy to unfriend and block someone from my content than on twitter.
Twitter gives no love in that area since every tweet is public no matter what. Anyone can latch on and make a storm of it whether good or bad. To be honest you have to have thick skin to say passionate stuff on that media platform and not go crazy.
As they say haters going hate.