At least the democrats here aren't monolithic, there are frequent initiatives at the local or state level to increase the supply but they've (sometimes narrowly) lost.
Also some of California's unusual policies (like the special property tax system and very high income tax) are actually due to a political system where ballot initiatives have more influence and weren't top-down planned by the legislature to begin with.
Anyway, yeah it does seem self evident. I think San Francisco is somewhat extreme relative to the national level though.