I think it has more to do with the societal tendency toward equilibrium.
In the early days of the Internet (initiation), it was so wide open and you could talk to so many different people that people eventually grew overwhelmed (oversaturation). People turned away from more public communication and self-publication methods (AIM, MySpace, etc.) to more private means (response/reversal).
In short: People are seeking a balance between a public "online" life and a private online life and the current trend is toward privacy. It will reach the next stage when Facebook inevitable becomes obsolete and irrelevant and is replaced by something even closer to the privacy end of the spectrum--like
diaspora.