Oddly enough whenever people start speculating about Primals, nobody ever brings up the cinematic intro of 1.0 where we see tons of Primals seemingly being "unleashed". I haven't seen any discussion about it since 2.0 and given a few of the theories in this thread I think it would be important to point it out as it confirms certain things such as Primals not taking the appearance of their followers but already having a shape of their own.

Here's the video.

Also, aren't Moogles pretty unique even amongst "beastmen"? Given how they, according to their own legends, descend from the heavens. Sounds to me like their ability to give form to an other entity could be due to their unique nature, I imagine we'll learn more about this in future content updates though.