The site also allows users 20 free article views a month, with unlimited free views if users come to the site from a search result or a direct link from another article or social media source. So, it's a rather nominal pay wall.
Of course, if one subscribes to the print (dead-tree?) edition of the Times, they will receive all the digital access they want.
Anecdotally, San Francisco has the second-highest subscription rate to NYT -- second only to New York. And the Times added a Bay Area supplement in October 2009
Newspapers have long maintained that pay walls are not necessarily revenue drivers, but more of a valuation of their proprietary content.