From our help section on the comment privilege:
You should submit a comment if you want to:
- Request clarification from the author;
- Leave constructive criticism that guides the author in improving the post;
- Add relevant but minor or transient information to a post (e.g. a link to a related question, or an alert to the author that the question has been updated).
Comments are not recommended for any of the following:
- Answering a question or providing an alternate solution to an existing answer; instead, post an actual answer (or edit to expand an existing one);
Nevertheless, instead of writing an answer people increasingly write a short comment only. These comments range form being a full answer of the question to a partial answer, or a link that answers the questions.
This is bad for the site as
- These comments cannot be downvoted. There is no community control to judge the value of any such comment.
- Whenever there is a comment that answers the question, people are reluctant to write an answer when it would have the same content.
We therefore will delete any such comment without mercy and irrespective of the value it may have.
If you come across any such comment please take the valuable information from it and copy & paste it in an answer. You can also post an answer to your own question this way. Then please flag the comment as no longer needed to bring it to our attention for deletion. Of course you may extend this answer if needed but even a short answer is better than none.