Why blog?

In the book Otherworld a virtual world is overlayed on the internet and is the subject of the book. Someone, somehow made a virtual world indistinguable from real life. During the adventure across 3 books. One character would talk out loud thinking that maybe, somehow her words would be recorded in a log that would record her thoughts and history. It was a way of the author to have a narrator without detracting from the story but it also parallels the wave of blogging.

Couldn't everyone just keep a diary on their computer? Having someone else read your opinion and being in a public area gives the writer a sense of importance. Another reason which I don't think is an intended benefit will be the ability to go back years from now and reading your own blog giving you a little insight as to your own state of mind.