There are two cohorts who dramatically overestimate Twitter's influence and importance - tech people and journalists. Twitter really is not very important. At my non tech workplace of 800 people, I'd be surprised if 50 were active on Twitter.
Some people have a lot more influence than others, and the influential people are disproportionately on twitter.
Also politicians.
That is the whole problem though, isn't it? A few hundred random people on Twitter are often more than enough to manufacture a wave of articles across multiple news websites and newspapers.
Twitter isn't important, the problem is that influential entities think that Twitter is important (and representative).
Which makes it important..