The lack of respect for new players.

[Soviet]

Ever flown a crowded helicopter into a building in Battlefield and get yelled at by your teammates? People get yelled at in other games and even in real life when they do something wrong. You may not like it, but at least you know not to do it again. 

Here is an example of someone who can't handle getting yelled at

 
Would you rather play with this person than 70% of the community?
You should be able to handle a bit of creatively worded criticism, especially in a game so reliant upon teamwork. Just accept it gracefully and move on.

If you get constantly harassed about a mistake you did, then that's someone else entirely. This usually done by other new-ish players, and not by veteran players (which is the demographic this thread is targeting). And besides, people get reported for that.