Correct. And in the process of doing so, further contributes to the lack of inventory of market-rate rental units available to the influx of newcomers/tech employees.
As mentioned elsewhere in the comments here, this causes huge disparities for rents of similar units within a given building as landlords attempt to compensate for all the market-rate rent being missed from longtime tenants. E.g. I've known folks paying $4,000 while their neighbors pay $400. While I don't have numbers or a study to point to, my experience over the years with the SF housing market suggests the impact of this effect is nontrivial.