While re-reading part of TJE to find a reference for another post, I came across an interesting line from Akka where he explains to Mimara why Seswatha left the Mandata his dreams:
"...by suffering the First Apocalypse over and over, we had no choice but to war against the possibility of the Second."
Akka boils down the Dreams to a way to keep the troops in line. A vision of something so terrible that you'd stop at nothing to prevent it. Much like Inverse Fire.
It's an interesting irony that mortal enemies like the Consult and Mandate use such similar "mechanisms of control".