Of course, but I think a large part of the incentive for startups to do that is so they can hire high-quality engineers who aren't in SF, so that they don't have to deal with the crazy cost of living expenses when paying salaries, and of course their own costs for living in SF and renting/owning office space there.

So I think I would expect most early-stage remote startups to pay salaries which account for an employee's cost of living (rather than paying a full SF salary whether you live in SF or Montana). But maybe I'm wrong.