I used to work at OkCupid, on OkTrends.
You're not the first person to propose this question - there's a comment like this almost every time OkCupid makes the front page - and here's what I wrote the last time[0], which I think explains it well:
There were a number of factors. A bit part is that, in 2010, there were 2.5 people working full-time[1] on doing research for OkTrends, which allowed us to research, write, and publish posts much more often.
The blog posts took a lot of work. "The Real Stuff White People Like"[2] took almost two months of my time, plus some from Max and Christian as well. (Much like the product design process, since we didn't start each post off with a clear end result in mind, not all the work was visible in the final product).
I left to go back to school. Max ended up taking on more responsibility for other data/stats work, which slowed the pace a bit, and he left at the beginning of 2012 to do his own stuff. And Christian became in charge of running OkCupid after the acquisition, which meant he had even less time then he did before Max and I joined.
People asked me for the last three years whether the reason OkTrends hadn't posted since 2011 was because of the Match.com acquisition and whether Match shut them down and I had to tell everyone "No, trust me, they're still around! It's just a coincidence!". Thankfully I no longer have to. :)
[0] https://news.ycombinator.com/item?id=8097780
[1] 2.5 full-time means: Two of us full-time, as well as Christian, though he split his work time between OkTrends (the blog) and other stuff.
[2] http://blog.okcupid.com/index.php/the-real-stuff-white-peopl...