I know about the Eternal September, but I believe that the AOL users that "swarmed" the network were more technically apt than the generic Twitter user and also were way fewer.
The skill (and motivation) gap between using something like IRC and Twitter is massive.
For some meaning of "limited subsection of the general population".
I had 12000 followers for a twitter account about a specific football club - a specific subsection but not a technical or media one.
I used to randomly look at my followers and while many were "highly invested tech and media people" - the majority were just people who wanted to stay up to date (in particular I used to live-tweet during games which lots of people really enjoyed).
That was a few years ago though - personally I rarely use Twitter any more.
We had that. It's called Usenet and IRC.