I like the term "playing house". Seems like there are a lot of similar activities. I don't make it to many "startup" type events, but when I do, I always wonder why everyone there is spending so much time hanging out with each other instead of going to the events their customers go to.
From my observations as a participant of such events, people actually working on startups don't frequent them. The composition of people attending your typical bi-weekly unmeeting is: few people with money, lots of people who would like some of that money, few random CEOs who look for free employers, and the rest that just wants to hang out with "startup guys" because it's cool (and maybe they get to see some new toy…
None of them will probably be your real customers but most of the people you'll meet are extremely interested in startups and new ideas. It's a crowd of early adopters, willing to try anything. This is worth something, at least while you're starting out and need to validate your ideas.
Compare that with pitching your startup idea to random people in a Walmart, that's way harder than it sounds :)