Earlier quoted context omitted.
Given that the talks are canned, and the materials they are based on are almost always published, why should I pay for a conference when I can already leverage existing networking/social channels to stay in touch with the latest ?
It's hard to go out for a beer with someone who isn't in the same place that you are. And people will definitely tell you stuff over a beer or two that they won't write about in their blog.
You do need a way to gather interesting people in one place, but you don't need a traditional conference (especially an expensive conference) to do so.