It's also utterly incomprehensible for someone who hasn't seen Haskell before. Whereas with the existing example, one can at least piece together an idea of what's going on.
The point is to demonstrate the directness of expression and conciseness of Haskell, not to show how to create an efficient implementation of an involved algorithm.
I agree that the first formulation is a bit incomprehensible, though two-liner breadth-first search is understandable if a bit amazing.
Some of the latter versions (and perhaps ultimately the very last version) are easier to walk through for a beginner, though, and are calculated from properties expressed in the first.
The point is to demonstrate the directness of expression and conciseness of Haskell, not to show how to create an efficient implementation of an involved algorithm.