The real difference is that non-urbanist lefties assume that the housing crisis is a *distributional* problem just like most issues in the US lefties care about. Unfortunately, it's not true that of housing and so abundant housing solutions sound non-leftist to them. https://twitter.com/JakeAnbinder/status/1279906077421834244
All good solutions to distributional problems have the feature that the richer you are, the more it hurts your interests. But housing abundance doesn't do that. It hurts upper-middle class retiree home owners more than penthouse owning CEOs. That's what trips lefty alarms.
This explains why so many non-urbanist lefties *assume* that there must be lots of vacant housing in low vacancy cities. That's the only way the housing crisis can be blamed on the 1%. It's downright axiomatic if you're working from the always-distributional principle.