Followups to answers, which is what you pointed out here are not Q&A Answers, and don't even appear on the Q&A answer page. You have to select a particular answer before you will even know that it has a followup. Many Q&A Answers have followups, usually offering corrections or additional information, but by in large, those followups can be ignored by the casual reader. QandAEditors sometimes use these followups to rework official answers.
anonymous contributions are currently not possible for Categorized Questions and Answers, but followups to answers are possible.
