the reason you keep citing Brayflox as some kind of gold standard to knowing how to tank is baffling to me.... you CAN pull larger groups in there, but nothing about the dungeon says you have to. There's nothing about that dungeon that serves as a training ground that forces the tank to grab larger groups, if anything it's a training ground for the tank to be aware of patrolling enemies.
You're both right and wrong here. Playing DPS alongside tanking, I never saw a wall to wall pull until I started running level 60 dungeons (I didn't bother unlocking the level 50 dungeons on my way to Heavensward), so there was no reason to expect that this was a skill I should have been learning and practicing up to that point. All I can say there is I was playing Paladin before leaving the game for about a year and a half during ARR, and never had to do massive pulls, came back, and decided to play with Dark Knight after getting to Ishgard, and just played the job the same as I'd played tanking in early ARR. So yeah, for me, at least, learning curve when it game to that, and coming late into Heavensward, I was running into, at the time, the issue of me being in item level 190 gear while the DPS I was playing alongside were closer to 230. The discrepancy at the time between what damage I could put out, even in tank stance, and what damage they could deal made holding hate a real challenge (not to mention also being yelled at for using tank stance in the first place)
So it was all of that combined that made me decide that the community is too unforgiving and demanding of someone who is low gear and seeing something different for the first time to even try to learn since I went from single packs being okay to being expected to pull everything in my poor gear immediately. This is something I could probably work on now if I had the desire, but that early experience soured me to even wanting to learn.