PyPI is the ground truth for a lot of the official information about packages, and package.wiki reuses some of it (like short descriptions) from the psf BigQuery dataset.
The initial idea was to do a fun data science project which builds some extra layers on top of that information - such as easier discovery, and showcase how popular the packages are.
It provides an extra context, similar to what https://bundlephobia.com/ does to https://www.npmjs.com