I actually don't think it's true, but it would take a large study to prove anything obviously. My personal experience was that it was much easier to have a fling or some other form of temporary relationship in NYC vs SF. Strictly for context, I spent a portion of my 20's literally living in both cities, without a committed relationship in either location. In NYC you could "get laid" relatively easily, but actually dating was harder. In SF there was more actual dating, which generally led to sex but it took longer. Which one you prefer is going to be a matter of taste obviously -- I actually preferred SF, the hookup culture felt pretty shallow to me. This was all more than a decade ago for me though, and everything I've heard about Tinder and such leads me to believe the hookup culture is pretty active in SF at this point. Life on the Peninsula is probably way worse for dating, simply because it's so much more spread out.

And now I need an anonymous posting button for HN. :)