This may not be popular and I think that this only applies to me - I'd not speak on behalf of others. I just recently posted a comment (I figured it was the solution but I like to check in the comments where applicable) and, shortly afterwards, a person took my comment and turned it into an answer.
Now, they also phrased it in their own words and they also gave some detailed information concerning the process. Also, had the answer worked, I'd have just linked them to a prior answer given that gave more information as I didn't see the question as valuable enough to write a full answer.
The thing is, I'm okay with it. Don't get me wrong - I'd not advocate that people do this, as a general rule, and I'd not suggest that others should be of the same opinion that I am. What I do feel is important is that I don't do it for the points, I do it because I'm here and learning already and this helps me to learn.
I do it because it's a way to give back to the community. I do it because, while I've had Linux installed on a second partition for years - I've never taken the time to really get to understand it as well as I feel I should.
That said... I think it is rude to do so to people who are not share the same views I do. I think that it is impossible for them to know that I hold this opinion and so they should not do this. While I personally do not mind, I'm quite sure that I'm in the minority. I think people should work to be polite in a community and that includes not pirating answers.
Personally, I don't mind. Just because I don't mind doesn't mean that others shouldn't mind and the default should be to assume that the act is unacceptable.
Additionally, if I've left a comment and not turned it into an answer in a reasonable time then, by all means, write it up as an answer so that the OP can find it more easily and so that future visitors can find it!
I'm not sure that I've articulated this well but I think it's different enough to warrant adding this as an answer. This doesn't mean that I disagree with the other answers - just that I personally don't mind if someone does it to me.
My goal is, first and foremost, to learn/adhere to the rules of the site while getting the user the best help they can get, in a timely fashion. My apologies if this is not expressed well.