Divine Detente is good for all lawful and neutrally aligned deities, but what about the chaotic ones? I'd poise there is a cost players can't see for Divine Intervention. If they want to blow up non-believers or dump demon armies on the universe, they risk war and spiritual starvation.
And with the forces of Law beating down the ones of Chaos, well, they can't make a concerted effort. Player-characters then become a hugely powerful pawn in this divine war just on cost savings alone as long as believers are an effective way to channel will into the universe.