I don't know. It's really just a cheap trick that makes half-assed advice sound much cleverer than it really is. But it works!

I really dislike these inverse guides -- they fight a strawman by negating an obviously false statement.

You see this in programming essays, where people show examples of absurd commenting (i++; // increment i). Yes, yes, we're reasonably intelligent readers know that's bad -- show us an example of nuanced commenting, or nuanced thinking!

Sometimes there is more than one "correct" method. In a lot of those cases, the "wrong" way is pretty specific, or at least tightly constrained. At such times, it is easier to explain that instead of explaining a large group of extremely different options.

Other times, it is just a simple case of "I don't know what works, but I know what doesn't work". This allows the next person to not make that mistake.