I can't see the use of this in almost any code. All of the "bad" examples they gave just seemed perfectly fine, and if they make sense to the user of the librar

I can't see the use of this in almost any code. All of the "bad" examples they gave just seemed perfectly fine, and if they make sense to the user of the library, there's no reason to disallow them. There are rare cases that actually call for keyword-only and (even more rarely) positional-only arguments, but unless they are required for your usecase, please do not enforce arbitrary argument types on your users.