If eligible landlords in SF all started raising rents by 7% per year, every year, the city would empty out. As much as housing is crazy expensive in SF, there's no way the market would bear those kinds of increases
SF already has rent control, which limits most landlords to increasing rent at 60% of inflation.
Needless to say, costs are increasing faster than 60% of inflation... In turn, landlords are only willing to write leases at very high prices and the supply of rental units is even lower than it would be otherwise...