Yup you're better off concentrating on building up your empire normally, then stomping the AI that way before it gets to the final ritual. So it plays like mortal empires anyway. If you could choose the cities for rituals it'd be better, but having a bunch of Chaos chosen doom stacks teleport in and head for the random cities the game has chosen gives you very little way of planning a defence. It actively discourages you from doing it.
Oof... worse than I thought. Mortal Empires provides much more variety, though I will say that most of the difficulty ratings are BS... no way in hell Khalida is 'normal'... -.-