Akatsuki?

[Zetsumei_Tsunarashi]

Moeru basically Yoshida wants primals to be big and powerful summons, they plan to have lesser avatars for the class/job.

Yes, Yoshida feels that XI's way of having 3 garudas and 5 leviathans roaming around in the same area makes the summons look cheap. He wants primals to be viewed as godlike, and so he wants it to seem like there is only one of each in the world, so therefore it can only be summoned one at a time.