the need for 3rd tank class

[Tashigi]

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.

GW2 problem isn't that you don't need a "tank/healer" but that the content is piss poor of a design.
End game content in GW2 is mostly zerg this, zerg that and there is little room for strategy.
There is a couple of things that usually require some cooperation/orientation and those are actually kinda fun but also made absurdly difficult with little reward in the end (I am talking about some of the Fractals).