Anyway, when that happened, suddenly there were a lot of bad tanks getting wrecked because they weren't maintaining good uptime on their defensives.... over time, there were less tanks overall.
Now, with M+, Tanks need to know routes (which change with affixes) and how to adjust on the fly to accomodate for mistakes as to not waste Prides.
Again, we saw plenty of "Bad Tanks" who aren't necessarily bad at Tanking, just bad at M+ routing.
Then over time, we see less Tanks as people give up due to the responsibility and or/the abuse when they get it wrong.
So no, I don't think it's a good design.
I think it's great for those who enjoy it, but it's made tanking a real niche which hurts the game overall.