This is kind of irrelevant though. Sure it should be documented, and sure the fence should have a nice notice of purpose posted right at the gate for everyone to see, but life doesn't work like that.
I'm not sure I'd go as far as irrelevant - rather, I would say that documentation is what you do to keep other people from needing the principle of charity. They're two directions on solving the same problem. As a maintainer you should assume good intentions, but as a creator you should work to clarify your intent.
