Comment by oefrha

Sounds like you just don't know ABCs, and "people who don't know ABCs don't expect ABCs to behave like ABCs" doesn't say much. Let me quote https://docs.python.org/3/glossary.html#term-abstract-base-c... for you:

> Abstract base classes complement duck-typing by providing a way to define interfaces when other techniques like hasattr() would be clumsy or subtly wrong (for example with magic methods). ABCs introduce virtual subclasses, which are classes that don’t inherit from a class but are still recognized by isinstance() and issubclass().

You simply don't "subclass ABCs" ever (except when defining an ABC); if you do it's no longer a virtual subclass and you're no longer implementing the ABC. As a concrete example, when did you last "subclass" collections.abc.Iterable? You did not, you implemented __iter__.