Why Doesn’t California Solve Its Housing Crisis by Building Some New Cities?

I think the problem is that the "build out" option is constrained by mountains and bodies of water (in the desirable areas) and lack of water (in the undesirable areas). Therefore, they would have to build up. This seems to trigger lots of NIMBY and it would have to be better constructed than in other parts of the US given that the ground can wiggle or even liquify from time to time.

And the bottom line is "who will pay for it".

If they are just going to build suburbs, don't waste your time. If they want to build human scale towns, like where they are walkable and multistory, then go for it, the tax base will make it worth it, but suburbs are a money pit.