Answering questions can be a collaborative process
Banning users from working together or sharing information leads to lower quality answers. Information is good and useful and can be used to build a high quality answer, but that isn't possible if there is no way to communicate.
As much as it would be great to think that each answer is totally independent and there is no iterative process, that isn't true.
It can be difficult to formulate an entire answer in 1 go. You need to read bits and pieces here and there, some from the core rules, jump through feat/class/skill descriptions, trawl faqs and erratas, look at designer tweets, etc.
Sourcing all of these pieces of the puzzle can be difficult. Posting a partial answer would be helpful for other users to incorporate into a final complete answer. Otherwise there is a situation where a number of users each know most of the answer, but no one has a complete answer.
Your choices are:
- Post a partial answer and accept that the punishment for sharing what you know is to be downvoted.
- Wait for someone else to post a partial answer, then comment presenting what you do know.
- Wait for someone else to post a partial answer, then incorporate their post into what you know and post your answer, downvoting theirs.
- Leave the thread alone, eventually someone will conduct enough research to present a complete answer.
Or, post the partial answer as a comment so that other answerers build on it. Once an answer is made then the comments can be flagged as redundant. I believe this is the cleanest and most effective solution.
On the main site you can comment partial answers
The arguments presented by Mxyzplk don't really hold up to any amount of scrutiny.
It bypasses question closes. They're closed for a reason.
And comments are allowed for a reason, partial answers are not answers. What's more, comments can lead to reopening when people realize that the question shouldn't be closed.
It provides an answer that can't be marked as an answer for future people's knowledge.
You can always make an answer, copy paste the comment, and credit the user
It contributes to long comment debates as you can comment on an answer, but it's unclear what you're commenting on in a comment thread.
By this logic all comments are bad.
It is "cheating" by locking your answer to the top. Answers with higher votes/accepted answers should go to the top to indicate their quality. Bypassing that by sticking your answer in a comment on the question is unacceptable.
Votes indicate popularity, not quality, and comments are not answers. Comments cannot earn rep and are ephemeral. There is no competition.
It bypasses all our quality control mechanisms: we can't downvote your "answer", edit it, or comment on it to request clarification or improvements. Answers also bump a question to the top so that people will scrutinize the answer; comments don't do this.
Comments are not answers in the first place. Every day I see people reply for comments asking for clarification or making suggestions.
It gets in the way of people who are busy using comments correctly to improve the question.
While SE's designer obviously has a lot of problems, you shouldn't actively make the site worse just to work within that problematic design. Barring multiple discussions in one comment thread is bad for everyone.