How is that a solution? Downtown L.A., for example, is not "full." And if you "densify" what are now single-family neighborhoods, that single-family neighborhood will simply move to the next frontier. Then the oh-so-horrible reign of terror will continue there. How does that help?

Zoning allows people to choose what kind of neighborhood they want to live in. If I wanted density, I'd live downtown. Why should developers be allowed to just roam in and destroy the lifestyle that the people in the area selected?