I don't understand...

[Odett]

The issue started up when they started to try to tell the tank want to do. The tank was not the one instigating the issue. Sure his skills may be limited or it could be that he was ungergeared. Who knows. But unsolicited advice will often end up with a mess.

This is exactly what I told a lv 42 PLD in Stone Vigil earlier today after he totally went off on the entire party. We tried our hardest to give him good advice in the most polite manner. He was using flash to pull and never using more than his 1-2-3 aggro chain on a single target in a group pull. Healer ended up tanking more of the dungeon than him. He started calling us backseat players and other stuff so we left him to his own devices. I eagerly await when he hits 50 and starts crying about elitists everywhere.

They tried telling the tank what to do because the healer was pulling enmity. If the tank was undergeared like you're assuming, then they should have used Flash more, since the healer had to heal more. This wasn't even a DPS issue, it was the healer getting enmity because the tank could not keep it, and if the healer does not heal, then the group wipes. Not every monster can be slept, like ispano pointed out, and that includes the Dragon Aevis, which is the hardest-hitting trash pull in SV.

They told the tank how to fix their enmity issue. You keep talking about everything being a collective effort, yet you insist that advice should not be given unless asked for, and that means having people adjust themselves to work around the poorest player (which was clearly the case in this situation). In order for a group to work in the most effective way, the least amount of adjustments should be made for that to happen. Suggesting to a tank that they should Flash more than once is a significantly smaller adjustment than having three people working around someone who refuses to press a button more than once.