In the last few days to weeks, I've come across multiple cases where someone commented on an answer with e.g. a clarification request, change proposal or other type of attempt to improve an answer. Subsequently, the answer's author or someone else replied, leading to a 3-4 comment conversation. Longer conversations, which are probably best moved to chat, are therefore not relevant to this question.
Anyway, after the changes were implemented, one of the participants deleted their comments, but the other participant(s) didn't, leading to a fragmented, broken conversation that makes little to no sense to other readers.
A specific example would be a conversation between me and NautArch on an answer of mine. He eventually deleted his comments, but I haven't done that so far*. As a result, readers can somewhat deduce the topic of our conversation, but it's certainly suboptimal.
* I would have done so by now, seeing how the remaining comments are more confusing than helpful, if not for this question.**
** They are now deleted.
Hence, what I'm asking is which course of action is more desirable: deleting a comment conversation for the purpose of tidiness, or keeping it for the purpose of documentation.
Note: this question is not about whether or not to keep conversations that already got fragmented - keeping half of a conversation is, in my opinion, clearly pointless. This is more about why the comments got fragmented in the first place.
Note 2: this probably also applies 1:1 to questions, but I've experienced the issue mainly with answers.