It is...after a fashion.

With high population a city gains levels. Every level gets you a boost in money, research, and production, dependent on type. Conclaves get a lot of research, and then a little money and production for example.

But that said, the actual population number doesn;t factor in. Once a city gains a level, its actual population number doesn't hold any bearing.

I would like some more possibilities with population end game. Sacrifice is too good currently (kill useless pop for free mana? yes plx) Tying level 5 city promotions to population someway would go far on fixing that issue. The growth issue is directly countered by consulates. (spam pioneers in low food cities for the big ones) My end game empire has 6+ outposts for every city, so lvl 5 is easy to get

Thanks guys. I wonder how the game would play if building upgrades required a step up in city level.