When I read old posts, I come across some informative comments below the questions which are off-topic, i.e., not aimed at asking for clarification, but they do add some value. I have noticed such comments being deleted under new questions for attempting to answer instead of using the answer box. I understand the reasons for their deletion which have been discussed in other meta posts, like this one, for example.
But what should we do with such inappropriate comments under old questions like the following?:
Is there a fundamental reason why gravitational mass is the same as inertial mass?
What's the difference between the five masses: inertial mass, gravitational mass, rest mass, invariant mass and relativistic mass?
To preserve such comments, I have once transferred them to a community wiki answer as per a suggestion given by a user in the main chatroom. But in the above cases, I think the comments (as such) wouldn't qualify as an answer, but at the same time, they aren't on-topic as well. These could be a part of an answer, but I don't think requests like "Please turn this comment into an answer" would not work as these old comments might be by inactive/deleted users. They have been there for so long and might have helped a lot of readers. So, is it fine to leave them as such and flag to delete comments only in newer questions? Further, were the criteria for an on-topic comment less strict or different in the past, as these comments are especially from high reputation users?
This question is directed towards old posts with informative comments, in general, not just the ones I have mentioned here.