I have a different experience. I don't know a single person who used to send life updates with email, or engage in mailing lists. At least to this individual, it was very obvious why Facebook was going to be a success when it arrived, it had all the basic 'tools' you needed to communicate and stay in contact with family and friends.
I think this is a very good example of why Facebook succeeded. Everything Facebook does was done (oftentimes better) by a niche tool with a niche audience of early adopters before. Facebook managed to cross the chasm with all of them and unify them together into a single social networking experience. It brought all these tools that were in use by small populations to the mainstream audience.
