In 1998, I started spending time on Table Talk, an online community at Salon.com. It's a general-purpose discussion forum, and at first, it was free, like almost all of today's "social media". But at some point, Salon had to start charging (at least for the ability to post) and Table Talk membership became slightly exclusive. Exclusivity on the 'net is kind of uncommon, and it creates a community with a very different purpose. It defines what you can and can't do.
After a few years I moved from Table Talk to The WELL, which is also owned by Salon and also fee-based. But in the case of The WELL, the exclusivity is greater. Whereas anyone can read any part of Table Talk without logging in, only a small portion of The WELL is publicly readable, and only members can post.
Over the past year, as I've immersed myself in other social media like LinkedIn, meetup.com, and Facebook, I've realized belatedly that The WELL's policies stand in stark contrast to what people expect on the internet. The WELL, and to a lesser extent Table Talk, is a gated community. It is virtually a castle with a moat and a drawbridge that takes credit cards.
Other social media services thrive on interconnection across their boundaries. Meetup.com encourages you to post your RSVPs on Facebook. YouTube lets you embed your videos promiscuously. According to this perspective, when you write a paragraph or upload a photo, you place no value on the content itself; the value it brings to you is in the conversations it starts. In The WELL's perspective, the content must be protected, either because it has value (it can be copyrighted) or because of privacy concerns. What you're buying with your membership is mutual agreement to adhere to the community standards that provide that protection.
I can see the value in both approaches. The truth is, I originally came to The WELL to be around intelligent adults, and I got that in spades - the level of discourse is high and there's real expertise in many fields there. But it's a timesuck, and now that I'm trying to be more focused in how I spend my personal time, I'm going to have to think hard about it when my renewal comes up.