Comment by Valour

It's not time, it's the number of people. There is a small range of numbers that make a valid community. Too few and there's no discussion. Too many, and they all compete to be heard like screaming children in a crowded lunchroom. It's a lot like a volleyball team. 1v1 doesn't work, 2v2 is meh, 3v3 up to 8v8 is fun. Any more than that and there are too many people and the communication process is too complex. Also, MMO game servers suffer from the same problems even though there is a hard limit to guild size and server population. There is no minimum, which sucks, and the maximum involves queue times and lag.

Here's a free startup idea for someone: Design an analytic process that determines the perfect userbase range for a successful community. It would have to scale according to niche. This would apply actual numeric goals for marketing campaigns. Instead of "the sky is the limit!" which we know is not true, you could provide an actual target and cut off membership (or start a second instance with an isolated userbase) at the maximum number.

Okay, now someone else do it, because I'm not smart enough.