>Most of Google's users weren't using search engines when Google was created.

I really don't know about your assessment about Facebook but I'd fundamentally disagree, as in the beginning they were capturing the college aged to young professionals. I'd say they fundamentally grew off the back of MySpace users. Myspace was huge and everyone had a page at the time.

Google was a little different as they did help to define and create this space of web indexing, as a lot of early search pages were more directories and portals.