Tanks were not balanced in SB, there was always the MT and OT issue, and in dungeons the differences and unbalance between tanks was gigantic
https://www.fflogs.com/zone/statisti...ps&class=Tanks
There were a ton of issues between tanks with Warrior and PLD having best single target dmg and best mitigation. At worst, DRK was doing 15% less single target damage than warrior.
The sustain between single and multi target was different between them too.
DPS jobs is a different story, because all what they have to do is to do damage and it is easier to balance than tank, which has to have some sort of sustain, have mitigation tools and damage skills and make them look and function different to each other but perform the same, this is a much harder job to do. So they decided to make tanks that way and not another.
Standard 1-2-3 combo, aoe combo, big deeps combo, range skill, dash, few deffensive CDs, Invulv skill, 1 party wide CD, thats it.