I will only say about the max level dungeons, as before that I'll just assume your are learning, but everyone that already have any job to lvl 80 should know how lvl 50+ dungeons works by then, whatever your base job, so I would be pretty ticked if you still single pull at max lvl. Tanking is just about going in a straight line, take 2 packs of mobs, pop 2 cd and aoe, it's probably the role with the less responsibility in shb as bad dps makes it hard for the healer to sustain his resources and the healer should know his kit and not spam cure1. Max lvl dungeons are supposed to be wall to wall, the healing is minimal and if you can't do it, there is a big problem and I'll wonder if you even tried to learn anything during your leveling -if you don't have any disabilities- (I'll not attack people in game, i'll just put music or a video and wait for it to finish). But people that defend those that actually can't support wall to wall pulling at max lvl are just ableist.

On top of that, saying a tank should be the one leading the pace is just giving even more stress to the stressed people too, there's no rule about that and if someone dont know the way (in a straight line and where 95% of the dungeons are just 2 packs per wall post lvl 50 somehow) you can just lead the way and if you pull it's way easier for them to take enmity with aoes.