Indeed, this phenomenon is not new, and most on-line communities are affected.
A good friend told me lately that she has been going through tough times, trying to "mend broken pieces" and to soothe things.
Besides trolls, hackers, etc., there are also certain "opinion makers", propagandists, pranksters or activists heating and blinding or destabilising various people, sowing discord among groups and friends.
And some others might be simply awkward, arrive at the wrong moment or place, say a wrong word, etc., or misunderstand something.