The thing about SF is that every neighborhood has its own "downtown" in the form a primary commercial street with coffee shops, grocery stores, small businesses, etc i.e. everything someone working from home might need. Also, nearly every neighborhood has at least one park that is accessible and walkable. When people say "downtown SF" they're referring to the eastern/northeastern part of the city with all of the office buildings which is ironically the part of the city with the worst selection of coffee shops, food, parks, etc. so there is really close to zero reason for people to want to be there. Working from home in NOPA, Inner Richmond, Haight, Duboce, Noe, etc etc is quite nice and also very walkable and convenient.