Part of the problem is that when rents are raised in a predatory fashion, the purchasing power of the renter is diminished.
Homeownership rate, 2006-2010 in SF County = 37.5%
Homeownership rate, 2006-2010 in California = 57.4%
Median value of owner-occupied units, SF 2010 = $785,200 (2000 = $396,400)
Median value of owner-occupied units, California 2010 = $458,500 (2000 = $211,500)
Rent control and rent stabilization aren't about low rent; they are about preventing landlords from enacting unreasonable increases in rent that are related to housing booms and bubbles. Renters really should be immune from the mortgage / interest rate speculation that drives housing booms and bubbles. Instead, the supply of renters is essentially leeched of its ability to invest its capital in housing for the long-term.
The topic comes up here so frequently; it's really astonishing how few people understand it.