The point of the article is excellent. It reinforces the fact that we as SQL programmers need to be careful and be sure of the results that our queries will return. It's a reminder to us veterans to not be complacent and whip out some crappy code when we're in a hurry. It's a nice lesson for new programmers who could easily fall into the trap of using the "Not Equal To" operator when they should really be using a sub-query or outer join.