Sorry for not being clear. I'm not attempting to redefine "documentation".

I was answering the OP's main question: "What kind of _information_ do you look for before learning/using new tech?"

You had answered "documentation" as one of the pieces of information. I was replying that "contrarian and negative" type of information is an important supplement to "documentation" or even a higher priority than official documentation. (E.g. The contrarian perspective may highlight a showstopping issue which could override any need to even look at the official documentation.)

My hypothetical of "dream documentation" including negative info was a utopian fantasy for rhetorical entertainment. It was not a realistic prescription for authors of real documentation.