Guiltythree
What you fool you truly are sunny, the clan create the citadels for their own benefit. They create the citadels in the dream realm for them to settle themselves and their clan. They do not do it for some mundane reason like creating a safe heaven for PPL. They only allow PPL in it because they can't manage themselves. They need soldiers and they need resources. They are only so much a clan can do that has only a couple thousand of population.
Theory the reason for the chain of nightmares is a large number of saints will come from this nightmare since a nightmare gate can be felt from the past and more awakend means more gates as well the saints can cause gates to form before they are even saints so maybe they will have a chance to fight the nightmare gates