Dude... you can't just decide what they use yourself. It literally has not happened. The Empire uses Primals because they cause massive amounts of destruction, that is more than enough reason to the people to support subjugation of them.

It was made VERY clear in the last two patches the the Empire's true goal of a unified race and world is a secret. Even the leaders of other nations didn't know. Do you think it's widely spread as propaganda, yet somehow even the Domans haven't heard of it? After they spent all year talking about how Imperial education and propaganda were shoved down their throats.

You are just straight making things up on your own now.