It's just a fun little quiz. I kind of like it as a "reality check" to show the reader that while they may understand the concepts, the reality is much more difficult and fraught with subtle considerations. It also serves as a subtle reminder to readers (who may be the frustrated business-type from the opening of the article) that there's a reason software projects are so hard and cost so much money. Software development isn't something you can grok from reading an article, even a book-length one.