The trouble comes when companies pay remote employees less if their cost of living is lower, or when they move to another place so they can pay people less. HP did that when they moved to Boise, ID.
CoL might be N-300% higher in SF but salaries (thank wage-fixing companies) are not. Salaries are (necessarily higher) but it's easy to dwarf the spread in normal, requisite expenditures.
CA has a high state income tax, relatively higher sales tax (than most midwest areas), and in the case of SF, the oh-so-obvious (self-inflicted) real estate problem.