Should I expect griefers on a regular basis at end-game?

[PennBlackacre]

I just finished my story quest and queued up from HM Ifrit. We pull, then apparently 1 of the tanks didn't properly interrupt some spell that caused to ranged to have to move or something. The WHM (Lady Yunalesca on Faerie) absolutely goes nuts and then says they're going to stop healing. After we wipe, they say that someone else should leave because they don't want the leaving debuff. We tried to pull it a few more times with 1 healer while this WHM just jumped around, but it didn't work out and the group disbanded

http://i.imgur.com/G2cZaei.jpg

Without a votekick system AND with a leaving debuff, SE seems to have created a perfect environment for griefers to get what they want. Does SE really care about this stuff or do they think that the playerbase will work itself out until only players like this person remain?