I'm lifting this straight from Photography.se as I think they have a very good policy on this.
I'm guilty of this too, but if it becomes policy then I shall also refrain.
Many times, short answers are posted simply as comments.
This has a detrimental effect.
The one instance* that has particularly raised my ire on the subject today is that after I had already posted an answer, someone decided to post a comment saying essentially exactly the same thing. If my answer wasn't sufficient, the comment should have been on my answer, or posted as a separate answer.
Then the community could decide which was the better one.
This reasoning from photo.se explains my thinking entirely...
When someone insists on continually answering question after question in the comments to the question it comes across to me this way:
I'm too important to be expected to submit an answer and have the community decide where in the pecking order of multiple answers it should fall. My answers should always be at the top of the page, regardless of how the other users in the community view said answers, and should be sheltered from review and correction by the rest of the community.
Can we vote on making comments as answers directly against policy & removable as 'unconstructive' if they are not working towards establishing an actual answer by requesting further detail/refinement etc ?
*no names, no pack drill. I am not going to single out any individual.
Re: Why do people post their answers as comments? I am not interested in 'why' but policy on 'whether it should be allowed at all'. Link-only answers, to which that post mainly refers, have their own policy already.