What do you guys think is the cause of severe lack of Tank users?

[SamRF]

but in ARR originally, the tank stance offered no extra enmity, .

Unless I'm having crazy mandella effect, I'm pretty sure Paladin Shield Oath increased enmity gain.

edit: Found a PLD guide from 2014, it did increase enmity, but also lowered damage by 30%, I'm guessing you're assuming that evens it out? I don't know for sure but I recall pretty well that generating enmity became easier when you unlocked Shield Oath, Brayflox being one of the most difficult to hold aggro since it was the last dungeon before you'd unlock Shield Oath.

[Vyrerus]

Unless I'm having crazy mandella effect, I'm pretty sure Paladin Shield Oath increased enmity gain.

edit: Found a PLD guide from 2014, it did increase enmity, but also lowered damage by 30%, I'm guessing you're assuming that evens it out? I don't know for sure but I recall pretty well that generating enmity became easier when you unlocked Shield Oath, Brayflox being one of the most difficult to hold aggro since it was the last dungeon before you'd unlock Shield Oath.

It had a lower enmity effect until 2.1, if it had one at all. I can't say for certain, because I did not play PLD until after 2.1.