Quote Originally Posted by Madoka View Post
It's basically the same thing.

A single human doesn't have the Aether to support a primal for any period of time, no matter how short. I don't expect them to break lore for your fantasy
That isn't the only reason.

In Final Fantasy XI, an Eidolon was basically a very powerful spirit being. Though technically a wild entity, that could cause great amounts of devastation if left to its own devices, with the exception of Bahamut, Odin, and Diabolos, they were largely benevolent creatures.

Primals in FFXIV are essentially vengeful gods of destruction. Nothing more and nothing less. The tempering process makes anyone who would summon them into their slaves. The only reason the player is immune to that is because of the Echo.