I mean Dian was another Goddess, and she was the one who wanted to make sure Gods were gone. So if anything it was her who caused it all.
That story though XD
I definitely would love to see in G21 a moment where the Milletian and the Divine Knights are too weak to get rid of the threat, and then the old Diety come in and just demolish everything. That could also cause the Milletian to possibly have new Demigod skills as well, so that we can defeat the enemies without having to rely on them.