The bad documentation I come across often shows every sign of having taken the advice from this article (and others like it) to heart.

The trouble is that the advice doesn't include ways to make sure your documentation actually covers everything it has to.

What this article says is that you should have « "API documentation" for every user-facing part of your project. »

That commonly leads to "reference" pages which are very little better than the autogenerated documentation the author dismisses. The main problems tend to be that behaviour that isn't controlled by a specific command or function or configuration setting doesn't get documented at all, and that commands with complex behaviour get described using terms that themselves need further definition which isn't provided anywhere.