But he could really step up by stripping building decisionmaking at the local level entirely, and have the state do it. Unlike local government the state cannot exclude disenfranchised voters (homeless, regional commuters) who would otherwise be living in say, San Mateo if they could vote for more development in the city.

The homeless are voters who have been disenfranchised by the cities they are homeless in? Commuters are disenfranchised by their local governments? ...what?

Prop 13 detaches property prices from taxes. On top of removing the disincentive to be a NIMBY (choking supply = prices go up = taxes go up,) that same mechanism makes it profitable to choke supply. Free equity to jack prices up, prices homeowners don't need to pay for. Of course they'd choke supply, and since "nobody opposed lives here," these local decisions choke supply via zoning and outright denial of even finalized building plans.

What are you on about? In your view, is “free equity” something that magically turns into cash? Because it doesn’t. All and any equity cashed out means someone sold their home...and if they sold their home thaf increased in value but kept low taxes, they likely couldn’t afford to turn around and upgrade in the city because their next property tax bills (and tax bill) would likely be way higher.

Adding supply doesn’t lower tax bills for other people... So there is zero tax incentive to be a NIMBY. (Just a decent one to be a homeowner so if you bought a $900k condo in 1999 when you retired you wouldn’t be expected to pay a tax bill like you just bought it for $1.4 million this year.)