I mean sort of. If the goal of leaving the a comment about the approach that didn't work is to save somebody time before they try that approach again, a regress

I mean sort of. If the goal of leaving the a comment about the approach that didn't work is to save somebody time before they try that approach again, a regression test is essentially asking the next developer to reconstruct a broken algorithm from thin air based a test. In my opinion, that's close to impossible. So the best case scenario is they re-implement the bad approach and it fails a test. They still wasted a bunch of time that could have been prevented with a simple comment.