You should work on your reading comprehension. What you're saying is precisely what the author is talking about: everyone has a story about terrible engineers,

You should work on your reading comprehension. What you're saying is precisely what the author is talking about: everyone has a story about terrible engineers, but they're almost always "elsewhere". Co-workers tend to become "stupid" and "incompetent" after you leave. And yet they maintain employment. It's an idea, not an iron-clad rule, that perhaps "incompetence" isn't as rampant as so many people suggest.