That’s… not documentation. That’s a CLI helpfile. It’s better than nothing but also what is completely broken with the “move fast and break things” mindset.
it's documentation enough to not call it an undocumented feature.
the concern with truly undocumented functionality is that it's not included intentionally: either it's a bug or an experimental feature that could be removed or changed with no notice. a poorly-documented feature, on the other hand, will probably at least get a deprecation notice before it disappears