[twic]

That would indeed be a terribly way to hire plumbers! But happily, that is not anything like what the article is suggesting.

The article suggests (1) using a simple but relevant exercise and (2) using it as a screen, to select people for a real interview.

The analogy with plumbers would be something like asking them to list the tools they would need to replace a hot water cylinder. For someone who knows their stuff, it's trivial. But it will weed out the guys who are bullshitting you. The guys who can give a good answer, you ask to come in for a proper interview.