This honestly sounds ridiculous to me. Every course I ever did we had access to years and years of past papers. Doing past papers is one of the best ways to study. Teaching or learning to the test is a good thing if the test is good.
Some professors would provide past exams for study aids or use them as homework problems.
However, the explicit default was that you should not look at solutions from prior years. Professors would announce at the beginning of the course that they reuse questions and looking at prior years solutions was an honor code violation. I think it's pretty clear it's cheating when the expectations are clearly outlined.
If you had inadvertently come across the problem before and independently solved it, you were expected to disclose that as part of your answer. I personally had to do this several times, and never suffered any negative consequences for it, but the expectation for honesty was there.
So why not just provide students with officially sanctioned practice papers that are not past papers and also guaranteed to not share questions with the actual exam?
If you write a new exam paper every year that is also guaranteed not to share questions with the actual exam. From a professor’s point of view many questions that are superficially different are similar enough to practically be the same question. There are many, many questions that ask about what the real cause of the French Revolution was, or test to see if you will recognize that this problem is basically a red black tree.
