Restricting AI death scale?

WRONG...
example: Using a car to travel across the USA makes traveling across way too easy when compared with other ground vehicles. Doesn't mean the car alone will be enough to acomplish this task.
just because one item, creature or spell makes the game much easier doesn't mean that single feature will win the game. There are many aspects of the game which work together.

That can be said for any nation, not just Ermor. Once you learn the weaknesses of the AI; then you can abuse them regardless of whatever nation you choose.

Where the AI works for Ermor is it doesn't mass produce priests, preach dominion and take domains, even for 1 turn, to stop the steady accumulation of forces by domain. Or using global spells and sieging castles with large Groups of reanimation crews and stopping the production of the 'elite' of Ermor.

However; even if you play on impossible with 17 opponents, on a mid-sized map, so you don't have the time it takes to sit on a Cache of provinces to create your armies you are going to have to work for it; unless you exploit the AI.

I don't know what your argument here is, if it's not that "Ermor is too easy if I use Burdern of Time too" or "I'd only play Ermor vs humans" (which means to me, other players).