https://sf.curbed.com/2019/3/21/18276227/vacancy-rate-san-jo...
So, yes -- it does.
If there were 10x as many homes for sale as are currently for sale, what do you think that'd do to the price of homes in the area?
Source: https://www.mercurynews.com/2019/02/14/the-bay-area-has-more...
I don't think high vacancy rates are the problem, I think they are a symptom.
Most of the people in this thread are only looking at the bay area from the past dozen years or so. In 2002, the picture was much different. In 1999, it was the opposite of 2002.
When you've lived in an area for decades, you can pick and choose where and when you buy. If you just moved there for a job, you're stuck without that time diversification and leverage ladder used by the folks who have lived there for a long time and accumulated many properties.