The problem is that the conversation never gets this far. By the time you start talking about upzoning a neighborhood with actual money in it, everyone who live

The problem is that the conversation never gets this far. By the time you start talking about upzoning a neighborhood with actual money in it, everyone who lives there will be screaming for the head of the head of the local city planning commissioner on a pike, and whatever land developer was interested in the project will quietly look for another poor neighborhood to pull a Robert Moses on. A lot of city governments are effectively gentleman's clubs: they serve the interests of the people who can afford to live and vote there, not the interests of the people as a whole. State or federal prohibitions on certain zoning restrictions might be a way to go around that, as the people who can't afford to live in certain cities would still be able to outvote those who can. I keep hearing California proposing to force city governments' hands on density; but it keeps getting stymied for stupid reasons. Having a "no reducing affordable housing units" rule should still be allowed, but a "no dense housing" rule should be banned as a clear attempt at fixing prices within a neighborhood.