Yeah, good point. The reason NPM can have packages like left-pad is that it works so well. It's easy to publish a package, it's easy to find one, it's easy to install and use a package. So sure, why NOT make a package for one function that you use all over the place?
There's a downside to all this, but ultimately it's to NPM's credit: the tools are so easy to use that people... use them.