Its pretty clearly you have not read or not understood OP concerns.
I will demonstrate to you something, look at this:
First numbers are coming from the savage raids in this expansion on this patch and second numbers are coming from savage raid from the patch before shadowbringers. These numbers represent the performance of all jobs in terms of pure DPS relative to all jobs.
You could see, tanks DPS performance dropped from 63-66% to 52-55%, its a 17% drop in performance in comparison to what we had back in the stormblood.
That means we lost on the influence, before a good tank would deal more dps than a bad DPS, and now even a good tank cannot surpass a bad DPS, and its really silly, especially if you realize that healers could deal almost as much dmg as tanks, when before they were nowhere near that level...
Tanks now are weaker than they were in the previous expansion and this is a hard and sad fact.
Also regarding team full of tanks.
No, if tanks were dealing 60-70% of damage that DPS do, you would still get only 1 tank, because deffensive bonuses are only valuable on one guy from the whole party, you dont need anymore tank than one, boss attack only one guy and cast tank busters only on one guy. Anything excessive in the deffensive department is a waste, i could guarantee you if team had any choice to which class should they take, they would take only 1 tank and not two like we have right now.