What if most of those followers are spam-bots? What if the candidate has decided to focus his/her Twitter feed on a specific area of expertise and thus is participating in one high-quality conversation with a few dozen people as opposed to hundreds of mid- to low-quality ones with hundreds of people? What if a candidate prefers face-to-face networking, or prefers not to publish his/her networking contacts publicly?

It seems to me that the Twitter count is merely a way for overwhelmed recruiters to quickly weed out job candidates, but I suspect they may be inadvertently tossing out solid workers whose quality networks happen to exist on platforms other than Twitter.