I wouldn't say it's "simple" and "without framework". It comes with jQuery, bootstrap, popper.js, and for some reason it has a lot of dependencies including "express" which is only for servers.
That's (part of the reason) why they are installed under devDependencies.
Thanks for the correction.
I use to hide the old docs domain.
Some tend to be fairly custom, so they do it themselves. Ours for example serves several apps in the same repo, with both HTTPS and HTTP, including some hot reload middleware and integration with our CDN for some live assets in development.
As for "why we have left-pad but not this", anyone can make a package. If you want to make a `uselessjs` package that does literally nothing, you can.