That hardly makes sense with the way SF’s rent control works — units that are currently empty “reset” to market rate when rented again. I’m in a rent controlled apartment paying close to $4k/month. Long-time tenants can see substantial benefit, but it doesn’t make any sense as a reason for places to currently be vacant unless a landlord is gambling that rents are going to substantially appreciate beyond $4k/month.

Unless you mean tenant protections in that owners are hoping to sell the buildings to flip to condos, in which case sure, they’re more valuable without tenants but that’s hardly unique to SF. Many places make it difficult to evict tenants to take rental units off the market.