I was in half a dozen SV companies, mostly startups but a couple big ones, between 1985 and 2004 when I moved away, so I have no idea what it is like now. But since you asked "did it ever really matter," here is my experience. I interviewed for my first job when I was wrapping up college. Two weeks after arriving for that job in Sunnyvale, they announced layoffs, so I had to interview again. Luckily, there were hundreds of companies within 15 minutes who were doing similar work, and found employment without interruption. Since then I have never had to really apply for a job again, and I've never been unemployed.

Back then, one recruiter or another called me about once every three weeks about some opportunity or other. People I worked with who had moved on would call to see if I was interested to join them. Or if I thought it was time to move on, there were many dozens of former coworkers I could call for leads. Those interviews were perfunctory -- that contact had already sold me to their boss, so it was really more about convincing me to join their company.

In 2004 I moved to Austin and things have been very different. I've never had a single recruiter call, and if I did decide to change jobs, I would have far fewer options than when I lived in SV. I'm nearing retirement age so I don't expect to ever interview again.