It's no mystery, the answer is right in the article itself.
http://www.eastbaytimes.com/2017/01/24/whats-behind-the-spate-of-recent-bay-area-restaurant-closures/
What?s behind the spate of recent Bay Area restaurant closures?
Upward of 60 restaurants around the Bay Area have closed since the start of September alone, with many citing difficulties like the cost of finding and keeping good employees, rising rents, new requirements for providing health care and sick leave, and doing it all while competing with the slew of new dining options.
In an industry where profit margins are slim, making it hard to raise wages or invest in recruitment tools, Bednarz explained, ?we have little leverage? when it comes to hiring.