I actually understand it. Ironically, a San Francisco resident Uber driver explained it to me. She said something like "People like the small city feel without over-population, people like the view from almost anywhere in the city - we don't want to to be another new your.

And while the skeptic in me sees "Property owners don't want prices to go down," I also see the other side now. San Fran wouldn't be San Fran even if we dug deep to have a ton of housing without ruining the view.

There is something to be said for not seeing a single police car until going South at night (or getting pulled over for going South on some street starting with an S "after 9"). There is also something to be said for living around people who can afford to live there (I can't, so don't take this as some elitist techie failing to check his privilige).