So this started happening.

[Legion88]

I don't know what you are talking, about but from my experience leveling Sage right now you have two types of tanks, yeah tanks, because it doesn't matter if DRK, GNB, PLD or WAR.
The first type is unkillable and doesn't seem to drop in HP at all.
The other type of tank is like made out of paper.
This is not a difference in their toolkit but the differece in player skill.
The first type is a god in using their mitigation and selfsustain and you can keep them up almost indefinitively just with Kardia DPS and a few oGCD heals now and then, even in big pulls. And you as a healer start asking yourself the important things in life, like am I needed at all and wouldn't it be better if I were a third DPS instead of a healer?
Then there is the other type of tank and reminds you of the hard reality. They leave holes in their mitigation uptime, use their mitigation randomly or not at all and taking huge unmitigated damage spikes in between their cooldowns if they use their cooldowns at all.
A good tanks makes the healer feel useless or happy to dps, while a bad tank makes the healer question themself about their choices in life and why they deserve this.

Now couple this with the prejudice of "DRK has no selfsustain" and many returning players that are not as good at their jobs as they think they are and healers less motivated with dealing with type 2 tanks will start avoiding them.