Provoke - Is it necessary?

[Remn]

Provoke is good for Boss swapping which you need to do in some instances.
It's a great tool anyways to have for emergencies.

In Garuda EX you swap the boss between you and the other tank to avoid getting 5 stacks of a debuff.

Provoke makes it easier to swap since it puts you at the top of the enmity list.

Are you talking about Ultima HM? Garuda Xm does NOT apply any debuff on tank. (aside from spiny plume)
Once you start doing the Xm Primal, Ultima HM, or Coil (T2, normal way) Provoke play really improtant part in tank swaping