There are certainly libraries out there that could do with better docs.
However, documentation written by people trying to get fake internet points with no skill at technical writing (even such things as the property capitalization of 'i' or running a spelling check on the non-code) increased the amount of work done by people trying to make great documentation beyond a tolerable threshold.
As the corporate goal of Documentation was to increase new user conversion, this additional work was overlooked for quite some time until it was recognized that the vast majority of the content was damaging the Stack Overflow brand and even discouraged the people who were trying to provide answers on the main site.
There's plenty of libraries out there that could benefit from something like Documentation.