You find this pretty much in most groups out there on the internet. Really the problem is electronic communication removes people from true interactions as well as accountability for what is said. If someone says something rude or harsh to someone's face, they are right there and have to deal with the reaction and consequences of what they say. Someone says something rude or harsh on the internet, there's very little accountability for their actions besides the other persons response in writing, which conversation can be ended anytime by either person, or just getting banned from the group.
There is also the difficulty with communicating through writing. Misunderstandings can happen much more easily through written communication because you aren't seeing and hearing what the other person's reaction and emotions are in response to what you say. Then there is the fact that people seem to just be much less tolerant of others with differing opinions these days.
So I would say if this kind of treatment and behavior of others bothers you, it's a lesson, to not behave in the same way.. Be more patient, tolerant, and treat others better.