I have a mono-repo where I wanted to run babel-loader in a certain directory & not everywhere, I've had a hard time finding how to do that.
Since there are lot more elements to blacklist here, it's good to have just a whitelist folder where we would want to run babel-loader.

Also this is what Webpack configuration doc suggests:

// Best practices:
// - Try to avoid exclude and prefer include

I think the intention of having exclude in the babel-loader documentation is to say explicitly about excluding vendor modules but it'll be good to also show an include example, just in case for people like me working on mono-repo or who just want to have a folder needed to be run using babel-loader & not the whole repo.

If agree, I'll be happy to create a pr