I think RHNA is an important measure to make sure communities like Atherton aren't allowed to externalize the cost of their lifestyle onto the rest of the Bay,

I think RHNA is an important measure to make sure communities like Atherton aren't allowed to externalize the cost of their lifestyle onto the rest of the Bay, but I think a land value tax coupled with dramatically liberalized zoning laws would be an even better solution. That way, people who "don't want to see their community change" would be free to buy up land and pay the opportunity cost of not developing it. Society could use that revenue to either invest in the welfare state, or offset taxes for the rest of us.