The problem is: The ToS have, if you read them carefully, nothing in them that forbids treating newbies like dirt as long as no expletives are used.
Calling someone a n00b? No offense, since not a curse word.
Telling s.o. he/she should better quit/is the worst player ever (not in general, I am talking about the very special context of a new player)? Cannot see anything in the ToS forbidding it.
Starting a dungeon with "oh, <player's name> again! The tank that cannot hold aggro!" (assuming the tank is new and does indeed have some issues) causing other players to consider quitting? No ToS clause about that, as far as I have been able to understand.
Bottom line: You can be as mean and toxic as you like, as long as you do not use any curse words. Nothing SE wants to fix, as it seems.