I was going to post this as a separate feature request, but it seems to go fine here: How about keeping obsolete (or something similar) and inform the comment’s author about such a flaginform the comment’s author about such a flag? If the author disagrees with the flag or fails to react to it within a certain time (e.g., 24 h), it is automatically converted to a noisy flag.
Compared to the current system, it shifts work from the moderators to the users and also reduces the work, as the author of a comment is usually more familiar with the situation and can decide more easily whether the flag is actually obsolete. In particular it does not create additional work.
Compared to the suggested system, this may create more work, but this effect is alleviated by the aforementioned effect of familiarity as well as the fact that the author of a comment can unilaterally delete it.
This reduces the chance that someone will not flag a comment as obsolete to avoid bothering the moderators, and may thus increase the number of obsolete flags. Whether this is a good or a bad thing can probably only be answered by experiment.
If users constructively commented on a post, there is a good chance that they are interested in the topic or, e.g., they are just waiting for a clarification before answering. Thus, such flags often coincide with an event that the comment author wants to know about anyway or they would have been informed of anyway (also see the point after the next). This also partially addresses the prominent feature request for informing downvoters about editsthe prominent feature request for informing downvoters about edits.
The most prominent exception to the above are arguably comments coming from reviewers. However, reviewers are performing moderating duties anyway and should thus be fine with a little additional workload from such flags.
It eliminates the need for creating another comment to inform a commenter that their comment has been reacted to (and is now obsolete). With other words, one could simply flag a constructive comment to one’s own post as obsolete instead of writing something like:
You are indeed correct about this information missing. I clarified this. Thank you.
As the post author in such a situation, I am in the dilemma between
- just flagging the original comment and thus risking that its author never becomes aware of my amendments.
- creating yet another comment, and thus more noise, to inform the original comment’s author about the amendments, thus risking that both comments remain (because the original comment’s author won’t delete a comment with a reply) or that I forget to delete my comment in time.
What I am suggesting avoids this dilemma and in particular the reason to make comments for the sole purpose of notifying other commentors about something. Something similar also applies to cleaning up comments after a longer discussion.
Most comments become obsolete, because they have been useful. Therefore it is usually slightly rewarding, if this happens: One has helped to make the Internet a slightly better place.
The only reason I can imagine why an author would refuse to delete an actually obsolete comment is that they are aiming for the PunditPundit badge. This could be countered by having deleted comments (or only comments deleted as obsolete) count towards this badge – though this probably requires a disproportionate amount of work.
This avoids the problem of having negative words such as noisy, unconstructive or similar assigned to good comments.
Some arguments are adapted from SevenSidedDie’s answerSevenSidedDie’s answer.