More evidence that social media drives people to be cruel, stupid, and callow. How is it possible so many people post publicly, or semi-publicly, content which would be considered crass, childish, and un-professional at best and fireable at worst.
I'd say it's more evidence that (many) people are cruel, stupid, and callow, and social media gives them the chance to expose who they really are. (It may also encourage their worse impulses rather than their better ones, but I think that they are bringing out who they already are. Social media isn't really changing them.)
People were always this way. Saying social media caused this is about like saying that ubiquitous video cameras in phones led to a rise in police brutality.