Why do other chaos factions hate you for vassalizing order factions?

Basically title.

If I as Archaon make Boris my vassal, I don’t think Azazel should get all angry because "Treaties with Bearman" but rather shouldn’t he be like "Cool you made him evil that’s like the whole thing we do."

Because isn’t that the point of chaos? The corruption?

I know there is a mod which solved this, but i don’t think it still works.