Which -let's be real- is nearly 100% of the cause of the insane rents in the area. [0]
> ...100% of the people who want to move to SF are competing on price for 30% of the inventory.
You make it sound like people never move out of a Rent Stabilized apartment. I know this not to be true. In my building, we get at least one entire-apartment vacancy every two or three months. Those apartments that are going for $3k+ per month that I talk about? They're often covered by Rent Stabilization. :)
Also, remember that SF's Rent Stabilization is the reset-to-any-rate-upon-loss-of-original-tenants flavor of rent control. So, once any Stabilized apartment loses all of its original tenants, [2] the landlord is free to set the rental rate to any rate.
[0] http://my.paragon-re.com/Docs/General/SixtyFortyImages/3-15_... via [1]
[1] http://www.paragon-re.com/Bay_Area_Apartment_Building_Market
[2] Known as Master Tenants, these are the first set of folks whose names were on the lease signed that established the base rate of that unit for that occupancy period. Tenants added after the initial lease signing do not count as Master Tenants.