I noticed that AI never DOW City-States directly like vanila warmongers do. All cases AI conquer some CS is due to his war with another civ allied with that CS. AI literally can sit on few poor cities and be surrounded by so many good spots occupied by City-States that he even cant never control and make no attempts to eat some of them. Even warmongers. I think it cripples AI developing a lot and making parties less interesting in a strategic perspective of confrontation with big warmongers. AI never attempt even regain their own cities occasionally conquered by some CS.