I won't be playing against people that intentionally break a houserule agreed before the game. If they don't make amends I'll quit the game. I don't play against cheats.
I only believe this if indeed a
hardlimit is given for the host, and it's not up to making agreements in chat...
Explain just how this hardlimit would work, can you? Because it adds a whole load of new problems that you have not addressed, please think about it and tell us exactly what you are proposing! Will the limit be just about settling your own cities? capturing neutral cities? capturing other players cities? What happens if you hit the limit and then want to capture another city? Can you do that? what happens when you have a quest to settle a new city or you need to build a temple to a god? Is the hardlimit still hard? Can you destroy any city at any time? What sort of hardlimit are we talking about? Say max of 35 cities per player for the whole game or does it only hold up to turn 100? What happens if one player wants a max of 30 and another wants 50?
Tell us and then explain why that is worth the trouble when we already have a working system that could be adapted by the houserules, as I proposed. Most players are honest and will stick to houserules. Those that don't will soon pick up a bad reputation.