The question is, how many of those people would have become Gmail users if not for Gmail's early success with the technical people. I do not know the answer to that (or even if it is an accurate premise), but one theory would be that in order to get non-technical users, you must first get the technical users, who will give your product good word of mouth and help it spread.
I would generally agree with you, but there are several popular services that I learned of from non-technical people. Things like tumbler, pinterest, snapchat come to mind. Lots of artsy social stuff out there that I have never used, but are used by non-technical people.
