Most of the time the info presented at these events could be found on the 'Net, likely faster and in more detail.
If information efficiency were the goal then that would be the way to go. But at the better gathering the talks or presentations are just a ruse to trick people into getting away from their homes or cubicles and interact in real-time with actual flesh and blood people. Serendipity takes over from there. That's why the best conferences have short talks and lots of breathing room; you want to prod people into talking to each other.
I can see the same thing with getting all your social info from a Webs site. Sure, Facebook will tell you when someone has seen a movie, but without that real-time, F2F (or even phone )conversation you miss the meandering dialog that bounces around into all sorts of areas you didn't even think to talk about until that moment.
The digital life can end up being awfully clinical. Lots of data, not much information.