I have been reading Marshall Rosenberg's Non-Violent Communication and according to that book - seeing people happy or seeing peoples interesting thoughts or seeing their appearance etc etc can all lead to comparative/judgemental thinking which leads to all kinds of unintended side effects. He references Dan Greenberg's book How To Make Yourself Miserable.

Yet to be seen if sites can somehow employ mechanics to reduce comparative/judgemental thinking...but its something they all intentionally/unintentionally fuel currently imho.