I can see how this would be true for a ramen-stage startup but it’s not true in the normal startup job market where engineers get paid six figures. Lots of good places available downtown for <2k per bedroom. If you don’t want a roommate you can get a decent small apartment for 3k or a lower-end place for 2k in other neighborhoods. You don’t need to leave the city, and you don’t save all that much by doing so anyway. Good neighborhoods outside the city are also expensive.

One good reason to leave the city would be if you prioritize renting a house with a 6000 sqft suburban lot, which you can’t find in the city. Another would be if you have kids and want a good school district.

That sounds rather implausible, given the average dev salary in SF and the existence of BART.

For example, living in Daly City would give you a ~30min commute, and the average rent there is $2,500, so $30,000 of post-tax income annually. High, obviously, but certainly doable on most SF dev salaries; Hired says the average there is 145k gross, so perhaps 100k or so after tax: https://hired.com/page/state-of-salaries