Ilberd

[Kallera]

It was also said that echo users are seen as enemies of the Empire.

Beastmen summoning Primals are bad, but primals can be defeated -at great cost- through conventional means.

That's hardly an answer even in Eorzea's case, as you are dealing with spiritual beings that can be resummoned when "slain", given enough crystals and faith. As much of a boon they have been, even the WoL is but a temporary solution that can just as easily die or be rendered helpless before a particular primal's assault.

when you take this from the view of an expanding empire, that will likely have more hostile enemies gifted with magic and more primals of their own, stopping primals permanently with a tried and true method becomes a lot more appealing. The attritiion of conventionally defeating primals would eventually incite more rebellion and a reversal of Garlemeld's fortunes as crystals and faith are a lot cheaper than the blood and treasure spent stopping rampaging primals of various strength.