It doesn't take much to get to critical mass... perhaps as little as 10 people posting regularly, assuming what they post is of interest to others.
When we started the board we had a rule for the Executive not to post on Chesstalk, only here. Of course it was different back then; CMA was a competitor to the CFC Store, which at the time supplied a huge percentage of the CFC's annual income.
I liked your recent thread showing the games, and it's given me an idea or two for other threads to start that people can post on.