I think part of the problem is that he's openly manipulative and exploitative, which regardless of whether it works, is going to put people off - if only because they don't want people to think they are like Ferriss too. (Though they still pay close attention; it's all very Hansonian.)

For example, I have something of a standing invitation from an assistant to write a post for the Ferriss blog about brain training and dual n-back; no compensation, of course, since the traffic is supposed to be worth it to me. And it probably is, because it's a popular blog - I suspect just a link in the footer to my DNB FAQ and other pages would result in a traffic spike greater than I've ever gotten from Hacker News or Reddit or LessWrong. But nevertheless, I've found it hard to motivate myself to write such a post and haven't written it yet.