Regard the following scenario. One asks a question and there are some comments, some of them followed up by others. In the end, all the constructive ones have been incorporated as improvements to the OP and the rest has been addressed but rejected or deemed irrelevant. The same process is carried out for the replies, one of which becomes the accepted answer.
What I usually do at this point is to remove all my comments and flag the rest as obsolete. Note that we can assume other kinds of comments not exist in the scenario.
Am I too nit-picky and needlessly sugar-coating or does that contribute with gain for the community? In order to matter, there's a need for a lot of others doing that as well, of course.