The shorter version of this techcrunch piece on SF housing is that for various policy reasons, the supply of housing in SF is highly inelastic, and there is an odd coalition of interests that are quite happy with that state of affairs.
Allowing more building won't magically halve rents, and the municipalities surrounding SF, specifically areas with BART stations, are probably bigger culprits than SF itself, but as long as demand keeps going up, changing policies to allow more housing construction is the only way at least moderate price/rent increases.
