User blog comment:Hakaishin Aro/Fate: Worlds Colliding/@comment-39280634-20190915190022/@comment-28144855-20190916101200

The catch is that as long as there is mortals inhabiting Earth (whole Nasuverse) You can't permanently erase the Evils, nor what the beasts represent, only their incarnations, their physical manifestations. The evils will eventually find a new vessel and the cycle continues. Basically a new guy will inherit the Evil and that's it.

As for the link, it's Wikia being capricious again...