... I'm talking about building new cities, which seems like the exact opposite of what you're describing?

Anyway, as far what happens when you make renting impossible (or just de facto not financially realistic), in Amsterdam it led to a lot of rentals being sold. The people buying had roughly 2x the income of those renting, on average. So, I guess that's a good thing, if your goal is to evict lower income renters so people can buy a place more cheaply. https://www.youtube.com/watch?v=t05cFv02pzY discusses this at length.