eryksun added the comment:
__doc__ and __module__ are also getsets (to support built-in types), but it's nothing to worry about since the attributes can't be deleted.
I think the most value added here is for listing __mro__ and the others that Georg mentioned. Should the following attributes be blacklisted from dir() as CPython implementation details?
__base__ __flags__ __basicsize__ __itemsize__ __dictoffset__ __weakrefoffset__
It's not as if people will miss what they never had.