Keep in mind that the word "rational" as used in this article does not have the technical meaning we use here at LW. As a software developer, I find that a lot of bug reports I receive come from that actual users exceeding all bounds of "rational" use of the software. And most of those, I fix, and I would have been better off with top notch testing department exceeding all bounds of "rational" testing to tell me about these bugs as I write the software and before it gets deployed to customers.
From The Black Team. (Hat tip to Adam "ata" Atlas and Mike Blume.)