the need for 3rd tank class

[Gamemako]

There is actually space available for OFFTANKS.

No, there isn't. You know what you don't see? 3-tank runs for Garuda extreme. Why? You don't need a third tank, and you do need DPS. Even if you for some reason favor the triangle method for Garuda, you'd be a fool to give up a full DPS for a gimped one just to do one trivial job.