That implies that these are things that Tanks actually need to do...
Enmity is pretty much a non-factor, it's just a case of mash your highest damage rotation in DPS stance and have everyone else de-taunt.
Mitigation is just "Use X button when boss uses Y ability at the predetermined time"
Positioning, is relevant occasionally, but there are a number of times when the boss just positions itself.
With mechanics, often actually having Tanks deal with fewer mechanics, since people who design bosses tend to make it so that DPS and Healers get targeted by crap that forces them to do stuff, while Tanks are often just sat there whacking away at the boss with maybe a cone attack to sidestep here and there.
It's a far cry from some of the great iterations of tanks from MMO's. Where things happened such as consistent high damage throughout a fight, meaning that a tank would have to continually space out their defensive CD's well to mitigate damage (Often weaving them between healer CD's) but ensuring that for the Tankbuster skills they had a potent enough CD available. Where threat was an actual thing that Tanks were in control of, where they'd try and optimize how much they used their major threat generators vs their DPS skills (Because while maximizing DPS was still important, it didn't happen to coincide with dealing adequate threat). Where tanks were constantly having to move bosses and adds in a fight and so the best Tanks could excel by moving as little as possible to deal with mechanics and minimize DPS loss from casters having to move.
As it stands now, Tanking in FFXIV is essentially just like playing a DPS, only you've swapped your DPS cooldowns for defensive ones. A lot of the time it's just sit there, follow the boss and maximize your DPS rotations. Maybe you boost your threat on pull with tank stance and an enmity combo before just going full DPS to mitigate high frontload classes. But otherwise, it's mostly just DPS stance, DPS combo, maximize usage of DPS cooldowns.