On my answer to a question the OP asked for some code clarification which I added and then told him that I did so. Both comments have disappeared. It's the first time I noticed something like that. Are these kind of comments ("Can you explain foobar a bit more? - "Sure look at the updated answer") routinely removed by moderators?
Comments are not considered to be 'permanent'. These comments, in particular, were flagged as being 'obsolete', and 'chatty':
I agreed, there was no reason to keep them after your answer had been updated:
- I love suggestion number 2 - I'm amazed I didn't think of it myself. Suggestion 1 is good too. Could you explain suggestion 3 more? It sounds really good, but I'm not sure I understand all you mean by the code being brittle and and how the interface would work. – Hosch250 22 hours ago
- @Hosch250: I updated my answer a bit – ChrisWue 17 hours ago
- OK, this is great! – Hosch250 10 hours ago
As a general rule, comments are 'ephemeral', and should not contain anything of significant substance.
Comments that contain relevant information should inspire an edit to the question/answer, and once the relevant detail is in the post (not the comment), then the comments become obsolete.
If you see an obsolete comment, flag it as such. There's a special flag reason for chatty, obsolete, or not-constructive comments.
2\$\begingroup\$ I'd just like to add a bit about why comments get cleaned up. Stack Exchange is all about getting a good Signal to Noise ratio, right? Getting rid of chatty/non-constructive/obsolete comments improves that ratio. \$\endgroup\$ Jan 4, 2015 at 12:31
5\$\begingroup\$ @RubberDuck Your comment should be edited into the answer and after that both our comments should be marked as obsolete and removed. Great case study. MetaMetaMeta. \$\endgroup\$– nwpJan 12, 2015 at 12:28
It may not be too common for moderators to delete others' comments on their own, but it's not much of a hassle on a lower-traffic site such as this. We may be mostly looking at newer posts, but another user may still encounter such comments on an older post and flag them for deletion.
In this case, as @rolfl has pointed out, those particular comments were flagged. We also cannot directly see who has raised a comment flag, but it usually doesn't matter.