If you are a programmer teacher, you could have a dozen of minimal projects that show very simple but complete examples of the libraries or frameworks.

Plus, some people fork all their dependencies in the case that the maintainer rage deletes them for some reason.

Most of them are archives, active only 4.

Probably NPM packages. I once saw a guy who was super proud that they "maintained" something insane like 500 NPM packages. They had custom tooling to make it possible.

Of course it was all less than worthless.