I've been in leftist housing advocacy circles. I studied urban planning.
1) Every leftist I know who cares about housing hates euclidean zoning
2) Every leftist I know who cares about housing hates down-zoning
3) Every urban planning class I took said that euclidean zoning is bad
Euclidean zoning is the principle land use regulation in the United States because it is supported by powerful people, landowners and yes property developers (who are also almost always land speculators.)
Thompson and Klein misrepresent euclidean zoning as a leftist project and then set it up as a wicker man to stuff with all the environmental and labor protections they want to torch.