I'm not sure why he included it in his list. However I do think that it does a very good job of bringing to light that your customers/users may not be appreciative of buggy code. They want something that "just works" and to not have to deal with vague error messages.
I started reading the book about a year into my first development job and it really brought to light the frustrations my users were having as I was seeing as it was just another interesting problem to me. As I said in my past post I haven't been diligent in reading it so I'm only a quarter of the way through but here's hoping I'll get more insights out of it when I pick it back up.
I do think that what this book talks about can be discovered in other ways, but for people who are just starting in the technology field it's a good primer to be aware of how others experience what you implement.
