Duncan Watts explains why he thinks Gladwell et. al are wrong about influencers. His thesis is that a trend can come from anyone and depends much more on the willingness of the masses to accept the trend than the “influence” of the individual. I think the core of the problem with influencer theory is that it’s often confused with reach, in other words, those who are considered influential are actually the ones with the most reach within a given community.
For those interested, here’s the PDF of Watts’ full paper: Influentials, Networks, and Public Opinion Formation (which I plan to read on my plane ride home).