[TulliusCicero]

Translation: keep out them poors.

Zoning that mandates low densities is used to economically segregate areas. They're invisibly gated communities enforced by the government. "Can't live here unless you can afford to buy/rent this much land."

One of the things I noticed while living in Munich was that the differences in apparent neighborhood prosperity in different parts of the city were vastly less extreme than in major US cities. Almost every neighborhood looked kind of vaguely middling, it was rare for a place to look obviously well-to-do or obviously run down.

And it makes that it's harder to get extreme differences there if at least medium density dwellings are allowed just about everywhere. Working class people may not be able to afford a whole house, but they may be able to afford an apartment in a given neighborhood.