I'm not suggesting it's common; it really depends what the beginner is doing. If you're just learning Python because you're trying to use e.g. a web framework like Django (that uses mixin classes all over the place), then chances are you'll put __init__ somewhere and run into this. If you're doing something else, you might never see this in your life. My comment was just responding directly to the parent comment though (pointing out a Python flaw), not trying to suggest every Python developer will run into this.