According to Jakob Nielsen
We are getting close to the bursting of Bubble 2.0, so it's a good idea to review some of the precursors of Bubble 1.0.
In 1999, I wrote an article "Metcalfe's Law in Reverse" about the problems of so-called walled gardens, where a service cuts itself off from the Internet and tries to add value by being closed.
[He said: 'Current attempts to split the Web into many isolated mini-networks undermine the long-term potential of the Internet which depends on universal interconnection.']
Facebook and the current generation of social networks are trying to replicate the walled garden strategy that failed ten years ago. It'll fail again.