I was talking about constant not having strategic resources in every game, not the joint wars. And yes, joint wars are broken, as they completly nullify the casus belli system. A joint war is both the war, and the justification for the war. Even from a logical/semantic standpoint that is problematic. but thats another discussion.
Not having resources is an artificial challenge and limits gameplay. On top of that, iron is not a rare resource, so thats not an excuse either.
Let them make the AI better to challenge us. I recently saw a screenshot where the AI build an encampment on a tile surrounded by 6 mountains... If maybe things like that were eliminated? Or coming back to joint wars, maybe if the AI was able to mount a decent attack when they declared war?
I actually never go for domination victory. On one hand because I find it boring and tedious, on the other because i never have the strategic resources for it, so your steamroll concern is totally irrelevant.