Almost since Twitter was noticed by marketers there has been a fascination with comparing who has the most followers, and so on. The general logic in this is that the more followers one has, the more people they can influence. From there all sorts of mayhem involving social media "guruship" based on a high follower count ensued.
Of course, just because you're talking at a lot of people doesn't make you influential. You're influential when other people take action based on what you say or do. And inducing someone to click the "Follow" button on your Twitter profile isn't much influence, really. When people refer to you, spread your messages and click on the links you share via Twitter, that's much more meaningful influence.