Wow. That’s amazing, especially for community package demos.
That was exactly my first thought, too! That was also part of this magic to me back then, when I searched for a package and boom an immediate fully running DEMO to discover the package’s functionality.
Client-only packages could easily leverage the npm package meteor-build-client and use GitHub docs but if your package involves any server code then you will have to use some server and now it’s possible again.