I think there is a big difference to being new, and just out right failing to learn. Im new to the game, but i am willing to hear advice and improve. I ran into a tank (in my story) who just flat out ignored the party.
I heard from my fc mates their experiences and some new player are just abrasive. They just outright refuse listen to do their role. Heard from an fc mate about a tank in a lvl 59 dungeon who refused to really use AoE, when asked to aoe in groups... tank ignore the fc mate.
now a days the concept of mmo seems dead. People just want to play by themselves, and ignore others. I recall my time in ff11.. and if you didnt play your role, you was kicked. If you ignored the group you was kicked.
in my story, the other party members just shrug off the guys behavior.
I think the intolerance comes from the above, just people refusing to work as a team. And vets are just tired of dealing with it. My experience was frustrating, im still learning how to play myself, and my role is very dependent on the tank doing theirs.