Answering in comments
This is an excellent question, and there are many sides to the matter.
Keeping the bar high makes the site useful — if our content was of horrible quality, it would attract the experts to answer and the enthusiasts to ask and read.
However, there is a network-wide tendency (strong preference from our SE overlords) not to allow answers in comments.
This is for various reasons:
- Comments are supposed to be used for improving the question or answer they are posted under. If you want to point out a related question or some other possibly relevant material, a comment is fine. If you want to ask for clarification or suggest an edit, a comment is again good. (If you are sure your edit idea is for the best, go ahead and edit the post.) An answer, no matter how partial or poorly supported, is an answer and should be posted as one. Answering in comments is against the idea upon which the site has been designed.
- Moderators are allowed and encouraged to delete comments that do not do what comments are supposed to do. Our on-site moderators do not enforce that actively, but SE community managers have moderator privileges on all sites. If you want your contribution to be preserved, don't post it as a comment. Comments have very low deletion threshold.
- An important feature of the site is that questions and answers are under scrutiny. Content can be commented and voted on. This does not work for comments: comments cannot be voted down, and other comments are not clearly linked to them.
- An answer given as a comment cannot be accepted. The SE way to mark a problem as solved is to accept an answer. What are you supposed to do if your question is answered by a comment?
- If you give a partial answer in a comment, there is a danger of "locking" the discussion. By this I mean that almost no-one will answer a question that someone has answered in a comment. Perhaps the key idea of the answer can be condensed into a comment, but if you do so, anyone who would like to give a fuller answer is easily discouraged since they don't want to steal your idea.
- There are many outside readers who end up on our site through Google or some other search engine. If you post a comment which three people like but twenty people hate, the comment shows a score of +3 and is right below the question. It sends the wrong signal much more efficiently there than as an answer (which would be promptly voted below other ones). People with no SE experience can be pretty clueless about how to interpret comments, answers, and scores — I have seen this first hand.
My strong personal preference, with which anyone is free to disagree, is never to answer in comments.
I would also prefer to enforce this (on many sites moderators delete all comments that answer the question), but I am not sure whether our users would appreciate that.
The fact remains that we have many answers posted as comments.
Opinions as answers
Some of the comment answers are opinions, but some also cite a source.
A quick comment like "Source X says the answer is Y." is not uncommon, and it would count as an answer as such.
When it comes to opinions, it is important to know that there are different kinds.
I like to classify it in two main classes: personal opinions and professional opinions.
For example, this would be a personal opinion: "I think Cicero writes better Latin than Caesar."
This would be a professional one: "My intuition is that you cannot use infinitives like that, and I don't recall ever seeing it."
Personal opinions are not that useful, but professional opinions often are.
The intuition of an experienced person is a great asset, and that asset should be available.
Some comment answers are guesses.
A typical example is "I am not sure, but perhaps X would be a decent translation for Y.", such as your comment to the linked question.
I would regard these guesses as expert opinions, too.
The community may disagree on some expert opinions, and that is inevitable.
But if your opinion is something other users agree on, then it is useful.
If another reputable user adds a comment "I agree based on my experience, but I have no hard evidence either.", it makes the point strong and the answer useful.
In many interesting cases there are no hard facts, so we cannot afford to refrain from giving opinion-based answers.
But those answers should be expert opinions and it should be stated clearly enough that what follows is not the ultimate truth but the intuition of a Latinist.
(See also this older question about opinion-based questions.)
What should we do, then?
I suggest some courses of action:
If you have an answer that you want to share, post it as one. If you feel that you don't deserve the reputation or you want to encourage others to improve, make the answer into a community wiki. This status hides the individual behind the answer (to some extent), allows everyone to edit with lower threshold, and earns no reputation points.
If you don't know how to make an answer community wiki (CW), please raise a flag, post a comment, or mention in the answer that you would like that status. The status can also be added to questions, and that can only be done by moderators. This is a low traffic site, so moderators are happy to help with any task like that.
If you see others post answers in comments, feel free to make use of them. There is nothing wrong with taking ideas from comments and posting them as answers. Attribution is polite, of course.
If you see a comment that would work as an answer as such, you can still post it as an answer. In this case I suggest making it CW; at least I don't think I deserve any reputation for copying someone else's comment into the answer button and hitting the "Post Your Answer" button.
Whether such opinion-based answers should be voted up or down depends on context. If you make it clear that it is your opinion but you thought it might be useful to share it, I doubt anyone is going to vote it down. (Sometimes some will consider an answer to be outright wrong and vote down, but that is quite rare. And that should certainly not happen with the two comment answers to the linked question even if they were posted as answers as such.) The criterion for voting is whether the content is useful and interesting. Being a guess or opinion doesn't disqualify, although such answers are likely to score lower than some others.
Latin Language Stack Exchange does not seem to have suffered from bad quality answers voted up disproportionally.
Less useful answers seem to end up with lower score.
As long as this is the case, I see no reason to be worried.
If the tide turns for one reason or another, I will certainly reconsider my view, but for now I see no good reason to refrain from answering with an answer if you have an answer.