These are things we know about beast tribe summons. The way the story is starting to play out though it seems as though there are a lot of things about primals and their summonings no one knows about, like Shiva's unique circumstances, Ramuh not wanting to temper everyone and Moogle not even being a technical "primal" (from my understanding anyways).

It wouldn't be out of line to find out there is a way to summon them that doesn't come with all the craziness we seen beast tribes do like tempering and being uncontrollable.

I could easily see them finding a way to control them and using them as a weapon against the Garlean Empire, Ascians, ect.