>> In reality, both dimensions are orthogonal, and vary in a continuum. Hence, you'll find super-coder assholes, nice incompetent people, and everything in between.

That is definitely true, but you don't get a uniform statistical sample responding to job postings.

The super-coders who work well with people don't come on the market as often.

  >> the author oversimplified reality to come to her conclusion.

The author's conclusion is that you should ignore one axis (I don't agree).