True. But nonlocal is relatively new.

Also nonlocal implies that other variables are local, which is not true. E.g., the following works without "nonlocal" keyword:

    counter = [0]

    def add(n):
      counter[0] += n

    add(1)
    add(2)

(This used to be my workaround.)

Yup, relatively new. Only around since python 3.0, for the last 12 years ;-)

nonlocal implies that you are reassigning a variable outside of the local scope.

Your example works because you are mutating an existing object, not reassigning a new one.

It's a disingenuous comparison IMO.