I see the number of children a couple has as a vote on how many people should exist on earth. If you have 0 or 1 child as a couple, you are voting that there should be fewer people. If you have 2 children, you're voting that there should be about the same number of people. If you have more than 2 children as a couple, you're voting that there should be more people on earth.
With that context, I can clearly see why nobody in a city would want to have more than 2 children.
With that context, I can clearly see why nobody in a city would want to have more than 2 children.