> But once everybody could broadcast, nobody could be heard.
Where do you get the "nobody could be heard" from? There was the rise of Myspace celebs, which I suppose could be a kind of early influencer. This had an influence on the direction that certain popular arts, like comedy and music went.
It's very hard to get followers on Twitter. Only a small minority of all users gets most of the attention. In the beginning, MySpace and Facebook were different, because they concentrated on real-life friends, but the trend is going in a few-to-many broadcast direction.