From Jonathan Rauch, guest blogging for Andrew Sullivan:
If some strange magnetic pulse wiped out every blog post written since the format began, hardly anything memorable or important would be lost; and, after 15 years or whatever, it's too late to hope for maturation. The medium is the problem. The Web is great for shopping and research, but intrinsically lousy for serious reading and writing. Over the past decade and more, the most striking fact about the blogosphere is how little it has produced of distinction or durability.
Oh yeah, that's going to go over well. It's pretty much true, of course, since your average blog post is about as durable as a story in a daily newspaper, and you know what they say about yesterday's news, don't you? It's also pretty much true of the weekly column writing business, though I suppose you can at least collect those in a book and pretend that they've found immortality that way.
Of course, some mediums are designed for posterity and some are designed to help readers make sense of the daily grind in real time. I hope Rauch hasn't gotten the two mixed up.