the need for 3rd tank class

[Assirra]

This.

Whoever first came up with this standard "Tank / Healer / Damage Dealer" locked-in role composition back in the Dim Ages of RPGs made a tremendously awful compromise that spoils a whole lot of the fun.

Please, go play Guild wars 2 and then say the holy trinity of roles was a bad idea.
There was no such thing as a group, you simply had 5 people attacking a boss at the same time.