Disappearing comment trails

Question

The trail of a wide number of different user's comments on this page has been deleted. I am wondering why and by whom?

The use of nominative "whom"

Some of the comments may have been primarily about the re-opening of the post (- which now of course, it might be argued, is not necessarily useful for the readership). However, the majority of comments were simply contributing to grammatical and syntactic debates surrounding the example sentence. These (imo) should definitely not have been removed.

Users, I feel, should also be notified when comments are deleted. Some notice period would also allow users to copy or store comments and responses to comments, either for their own records or so that they could be incorporated into answers or new questions.

[An entirely different point here is that it would be helpful, in such instances, for comments regarding the viability of the post itself to be archived somewhere where users interested in the the meta-processes and editing history of the question could access them. This would provide some transparency as to the reason users and moderators have voted to close or keep posts open and inform readers about the quality of the moderation processes.]

Answer 1

The parts of your question that focus on comment deletion notification is answered in this post. It also touches on the myriad reasons why comments are deleted.

You kindly asked why that specific comment chain was removed, because you felt that the comments were contributing to the debate surrounding the example sentence.

Comments are not for debates or discussion. Comments are intended as brief messages to provide feedback, add minor information, ask for clarification, or discuss the content of the post with the intent of improving it. Comments are temporary. You should not think of them nor use them as a vehicle for information that is worthy of archiving.

As such, I removed 40 comments from the question because they were inappropriately placed. I incorporated the relevant parts of the commentary into the question to replace the OP's "see the comments" edit. I think it's a fair assessment to say that the argument you were making was an answer on its own.

The comment edit history is not available and to my knowledge, deleted comments cannot be retrieved.

As for editing and whatnot, the edit history and the comments are all timestamped. If you want some more features than that, I encourage you to post a feature request on Meta.SE.