That's my current approach to teaching people programming concepts. I try to provide an example of not using that concept, point out the quickly growing complexity of the code, and then show how that complexity can be reduced with the new concept I'm introducing.

(And yes, as a kid, I was hurt by all those "Cat : public Animal" examples too. It took me many years before I figured out why they didn't work in practice for me.)

I think this is why you often see people reinvent GOTO. Everyone who started with BASIC (and moved on) knows why you won't do that any more. But someone today starting with python might not understand. [replace GOTO with any bad example]