If you insist that `len` shouldn't be defined on strings, and the default iterator should be undefined in python then:

  for c in "Hello":
    pass

should throw an exception. Also

  if word[0] == 'H':
     pass

should throw an exception.

This would have been an extremely controversial suggestion when python3 came out to say the least.

Codepoints is a natural way of defining unicode strings in python, and it mostly works the way you expect once you give it a bit of thought. It is lower level than, say, grapheme clusters, but its more well defined and it provides the proper primitives for dealing with all use cases.