I agree in principle, but there are exceptions to that rule. Lonesome Dove, the example he uses in that article, is one of those exceptions. He clearly hadn't read the book before writing the piece, and now I'm waiting for a retraction along the lines of "I was so wrong, I wish there was twice as much of this amazing book."

But yeah, in general, I think most books could be shorter and still be as effective, often moreso.