Suppose I place an answer comment (e.g. elaborate your answer, don't provide only a link bladibla) and the person adjusts the answer and it's worth a +1. Meanwhile, my comment has been upvoted as well, but is now, obviously, obsolete. Do I remove my comment?
Yes, indeed. What's more, if you find such comments posted by others, flag them as obsolete. Comments are supposed to be transient and mods can and will delete them without warning.
Such flags help keep the site free of clutter and give mods a warm fuzzy sense of being useful :)