This sounds like a failure of your teacher/grader, not like a failure of the idea of plagiarism, though? > Focus on idea sharing. On how to explain complex ide

This sounds like a failure of your teacher/grader, not like a failure of the idea of plagiarism, though? > Focus on idea sharing. On how to explain complex ideas to your classmates. On how to build consistent abstractions or arguments. 100% agreed! And I think most cogent interpretations of plagiarism would say that if you're able to do those things then you're not plagiarising, you're building off of other sources (providing that you cite them correctly). (It's entirely possible that I've been lucky, and that my teachers/professors took unusually rational stances when it came to this kind of thing. But it feels like you're presenting a false dichotomy.)