... I can see why she does it.
As soon as I mention my major from back when I was in college to anyone still in college there, they immediately ask, "Do you still have your lab reports from ____ class?" This has happened to me more times than I can remember, and I graduated from undergrad more than 5 years ago. No, I do not have my Mammalian Physiology or Organic Chem lab notebooks stashed away in a vault.
I understand that the lab classes are difficult, but if you're so desperate for someone to cheat off that you have to ask some random dude at the gym who started a conversation with you about how to do squats properly, there's a problem.
Cheating and copying of former students' assignments is probably rampant. Is this a real solution? No. There are way too many ways to circumvent her system, and it's morally wrong.
A better question to ask is why doesn't she change her tests or assignments or such so that past notes don't matter? It's not like Economics is a lab class with experiments that are difficult to change from year-to-year. If students are collecting old notes to help them study, what's wrong with more study materials so long as they do not allow the students to cheat?