> Because it is so few lines it is much more sensible to have everyone duplicate that little snippet manually

Mine's about 100 LOC. There's a lot you can get wrong. Having a way to use a known working version and update that rather than adding a hundred potentially unnecessary lines of code is a good thing. https://github.com/mikemaccana/fetch-unfucked/blob/master/sr...

> import a library and write interceptors for that...

What you suggesting people would have to intercept? Just import a library you trust and use it.