The stale old enterprise code is not in public repositories.
Javascript made the barrier to entry for creating a package nearly zero. In contrast, it's fairly difficult to publish something on Maven Central (the main Java repository). You need to prove you own a domain, setup a GPG key for signing, manually register with Sonatype, which is more than many people are willing to do. I think that explains it much better.
That might be the case, but the libraries seems to be more reusable!