I've noticed on a few posts I've been involved with that an answer will be provided and the question/answer author's post will be edited enough to make the comment thread irrelevant.
- A back-and-forth asking for more detail, and then the question/answer is updated to include the requested detail
Issue to address
In these cases, I've found that the comment thread makes the normal "flow" of the question harder to engage with because the comments don't sync up with discussion that is relevant to the question/answer as it currently exists.
This also leads to excess comments that are no longer necessary. Their existence has the potential to inhibit the learning of SE users, or at least the potential to consume more time than necessary.
Potential ways to address this
Others likely have better ideas on how to handle it, but some potential suggestions:
Commenter-based moderation: Allow an option on "delete" to be that it's no longer relevant under the current revision. This would allow the comment to be preserved but linked to the previous revision of the question without showing up in the current revision.
Mod-based moderation: Allow mods to do this with bulk comments so that whole comment discussions can be moved to the correct revision if
Author-based moderation: Upon revision of a question/answer, allow the author of a question/answer to identify which comments will become irrelevant as of the update.
Thanks for letting me muse a bit.