I love the last few paragraphs of this article, unfortunately, I've managed enough people to know the value of nerf guns/ping pong tables...
Ping pong/foosball/assorted games have a wonderful place in startups. Case in point - welcoming new employees. New people tend towards shyness. Cutting through this shyness should really be the first step in onboarding new people. Guess what? One game of foosball/ping pong is better than three (usually awkward) lunches with a supervisor/other coworkers...
Then, there is the struggle. Ben Horowitz wrote about the struggle from the perspective of founders, but startup employees feel it just as acutely. Ever been stuck at work, late into the evening, desparate to complete a project? Ever go out with friends from university and discover that you make 25% less than the rest of your group? Ever work for a company that has pivoted so many times you can't remember what you originally signed on to build?
Good founders and an environment built upon respect and open communication can go a long ways towards reducing the struggle. However, when you're in the thick of it, a couple of games of ping pong can keep you moving forward (or keep you from applying to any of the 35 other startups that would hire you)...
Finally, there's one other wonderful business reason for mixing work and fun. Retaining your talent. Really good people (aka - the people you need in startups) have all kinds of options. If they have fun where they are and work with close friends, they are less likely to quit.
All in all,decent article. Unfortunately, it overlooks a huge number of situations when ping pong actually becomes important.