This is related to many specific topics, e.g. Cleaning up comments from migrated questions.
Some comments are good and they result in actionables, e.g. migration, but perhaps more often revision to answers that considerably improve it, perhaps by pointing out errors, corner cases, slight inaccuraccies, caveats, etc.
After a point, though, these comments just becomes noise. After, say, a question is migrated, all the comments that says "this belongs here/there" are obsolete. After, say, an answer is revised and all concerns addressed, a comment to the effect of "it's better to do it this way" or "you forgot to take care of this case", etc are obsolete.
(Focusing on comments on answers now) When these comments remain, they distract from the answer, because everyone would be drawn to the comments and see if there's anything that really adds to the answer. If the system works as they should be, then NOTHING new should be in these comments, because the main purpose of these comments is to provide feedback so the answers themselves can be iteratively improved.
Ideas? Comments? Feedbacks?
Example scenario #1
Recently I left a comment on an answer that raised valid concerns, and the answerer "revised" the answer with an annotation that says "okay, this part of the answer is wrong as the comments suggested, but I'm leaving it here so the comments aren't orphaned".
This is a less than ideal outcome of the commenting process. If obsoletion (and eventually deletion) of comments becomes commonplace, then the best course of action in this case would be to incorporate the discussion in the comments into the answer itself, e.g. "we can attempt this solution, however it doesn't work because of such and such factors". There's no need for an answerer to keep a wrongful claim in an answer (even with added disclaimer).
Another potential outcome is that the answerer could've edited out the problematic part of the answer completely. This is less than ideal, but not because it'd make the comments look "dumb", but because the concerns could be re-raised in another answer.
Answerers should never be discouraged from making good, valid comments look "dumb". In fact, they should strive to do that always. If there's a problem with the answer, then fix it. Yes, the comments would then look "dumb", becomes "redundant", adding just "noise"... and that's why we're having this discussion on meta.
Good comments are purposeful ones. Once they've served their purpose, they become obsolete. There needs to be a way to clean the obsolete ones.
(By the way, I was more than willing to delete my comments had the issues been integrated into the answer. In fact, I've recently started doing this, i.e. raising points in comments which I delete once they're addressed. It's hard to keep track of which of my comments have been addressed and which haven't, though. Perhaps answerer can leave a comment to alert me, e.g. "hey thanks for the feedback, i took care of it and i've deleted my comments in our discussion so you can delete yours now", but that creates another comment that eventually becomes obsolete. This may be okay, though, because a back and forth of 10 obsolete technical comments may be replaced with 1 simple "thank you" comment... which may itself be cleaned up eventually one way or another).
(Of course another valid point is that such discussions should've never taken place in stackoverflow in the first place, but some topics are tricky and honestly good discussions take place anyways...)