In the review page for low-quality posts,
When reviewing answers (at least) it is sometimes the case that the answer is in fact a comment by a low-reputation user. While voting for deletion is fine, and even leaving a comment is fine, I think we should be allowed to flag this for the moderators to convert the answer to a comment.
Sometimes it is useless, e.g. when the answer is just another question. In such case there is nothing to do except leaving a comment and [voting for] deleting. But sometimes it's reasonable to flag the answer.