I don't disagree, but there are ramifications. A big one being sprawl. If existing urban/suburban areas are to remain stagnant, then development will just pus

I don't disagree, but there are ramifications. A big one being sprawl. If existing urban/suburban areas are to remain stagnant, then development will just push outward into areas where land is cheap and landowners more than happy to pocket a nice chunk for their former farmland. Wrap an urban growth boundary around the city, and then you can stop some of that and instead watch your housing prices skyrocket. Wait a second, I think I just described Portland.