[mtviewdave]

>...it emerged in SF...

It didn't emerge in SF. Quite the contrary, virtually all tech startups for most of the Bay Area's history were no farther north than Menlo Park, and often much farther south (Netflix was founded in Scotts Valley). That's why YC was headquartered in Mountain View until recently.

SF only became a startup hub within the last decade, IMHO in response to the desire of Millenials to live in urban environments.