If the game designer produces more content than he can consume per month, some fraction of the people will say more quests, more tests, more challenges, more whatever, and they will be compelled by it.
If you're building a social product, you're still living in the last century if your product doesn't work on Facebook.
Think of Slide as a giant media network for people to transmit information. The content that's in there now has been provided by users - it's whatever they want it to be.
Technology has come a long way since PayPal.
If we compare the two, Facebook is currently a superior place to market a product like Slide. Twitter is more like a general distribution agent. It's like broadcast radio.
If I see what you're up to on Facebook but I don't see your updates on Flickr, I'll still care about Facebook.
