It's not just whether it exists though. Too much documentation is a thing as well. In a way it's worse, because the reader can't find the thing they are looking

It's not just whether it exists though. Too much documentation is a thing as well. In a way it's worse, because the reader can't find the thing they are looking for, but the author can always point at where it is when asked. So then the author becomes the index and wonders why they keep getting asked.