I see tanks come into higher level dungeons even before 50 in a hodgepodge mix of starter accessories and NQ quest gear from... anywhere between 5 and 10 levels behind the dungeon. I'm a pretty good WHM, I'm easing back into it on my new main as if I never left the job in the first place - but no matter how good of a healer you are, you can't save a tank from dying in two hits when they have less HP than the NQ-wearing baby Summoner.

Minimum iLevel should most definitely be a thing. Considering how it can lock you out at endgame to not have a proper iLevel, it isn't unreasonable to have the game start teaching newblets about it very early on. >_>;