You missed the intro

  I'm trying to write a blog post for O'Reilly publicising
  the tutorials at CUFP, and was going to structure it
  around "10 reasons for not learning functional
  programming" rebutting each of them. Here's my list of 11
  (so far) … any more ideas?

It says at the top that he's trying to compile a list of common "why not FP" arguments so he can rebut them, as part of publicity for an O'Reilly series on functional programming.