I explicitly stated that FB has its positives. But wasting hours doing anything is bad. FB stalking people != stronger ties. It's a problem many people face, along with excessive gaming, etc.

I criticize the assertion that changing weak ties, in the way FB does, is a net positive for society. It's one thing to reconnect with an old friend, it's another to spend time everyday browsing through pictures of people you haven't seen in 10 years. Too much of the latter happens on FB.