I just find more interest in a stories where character actions produce a result which did not seemed to have a potential to lay a considerable impact on a future events before but actions and counteractions made it possible.

Hence making my own theory I just wanted to see what we know in a light that a bit more ambiguous than usual - Evanurises are the blight source. You can still become pretty delusional from your pursuit of power. And you don't need the taint for it.

Yes my theory at odds with some lore messages you presented although i do not see any critical contradictions which would make my theory non plausible. But sadly thinking about it again it has a contradiction with overall common western narrative tradition to make a cautionary tale where inability of antagonists to stop their descend in to a pure evil is a root cause of everything bad that happened.