For a decently established startup with well-secured funding, this article is spot-on.
Many founders find missing their friends and hobbies makes them less productive, so, for some, it's far better for the startup to spend a little less time on it. It takes a very self-aware founder to actually do it though.
In a perfect world I would probably only socialize once a week, with a good friend each time.
I really should make that a higher priority, even if some travel is required.
There's really no substitute for a real friend.
DHH not only open sourced Rails while he built 37 Signals / Basecamp he also won Le Mans racing trophies and wrote a couple books on entrepreneurship.
Sometimes there are situations where it truly is a matter of hyper growth and full bore competition, but I think there are plenty of opportunities to build a sub-billion dollar business and still have an interesting life outside of work.