When was the last time SF had too much housing? Obviously prices have gone down at times in the past but it's hard to argue there's ever been an oversupply....
Parent said that SF has to "plan for the long term, like when the boom turns to bust and lots of those new residents leave."
I don't think that's something that needs to be planned for. Even in a worst case scenario there will be plenty of demand to fill up any the new housing that's coming up in SF.