If you're going to wrote a blog post on the topic, probably worth spending a few minutes double checking your understanding of the "thing". I don't doubt that the author may have been taught the wrong thing, but to write an entire post starting from and remaining in a state of misunderstanding is not particularly useful.

The entire point of the article is that his original understanding of the “thing” was a misunderstanding, with a heavy emphasis on how his teachers led him to that misunderstanding.

Author used a rhetorical device that you seem to have missed.

The article brings with an incorrect premise, and then argues a different point.

The opening premise is: NP-hardness is easy in theory, hard in practice, the point made is that it’s easy in practice. But that premise is itself wrong: complexity theorists know that NP-hardness is in fact, hard in theory.