AI "Team" not teamworking
There is an option in game setup to have AIs belong to "teams". I'm not sure if this is WAD, since the respective AIs do not treat each other as such. While I cannot speculate as to how often they trade resources with one another freely, I can see that it is quite easy to wage war against one team member and have pleasant relations with the other. This, at least, in my opinion should not be possible.