Is it permissible to cherry-pick someone else's answer for the same question?

Question

Concerning Are 'tree waterfalls' possible?

Some time after answering the question myself, I found LazyReader's answer had been deleted. However, I felt the answer had intrinsic merit, so I edited the answer to address the issues brought up in comments and voted to reopen. I was delighted to see it reopened.

One hour later, Nathaniel edited his answer to (IMO) cherry pick information he liked about LazyReader's answer, extend it a bit, and repost.¹ This started a bit of a spat between us because I'm not a fan of cherry-picking anybody's answers without permission. Nathaniel challenged me to cite policies.

From "The Editing Process" we read:

All contributions are licensed under Creative Commons, and this site is collaboratively edited, like Wikipedia. If you see something that needs improvement, click edit!

And from "Expected Behavior" we read:

Provide better answers of your own. Last but not least, edit and improve the existing questions and answers! By doing these things, you are helping keep Stack Exchange a great place to share knowledge of our craft.

But, although the disfavor of cherry-picking has been acknowledged in comments for years, there isn't a specific policy per se that I can find that specifically admonishes against it.

Question: Is it permissible on WorldBuilding.SE for one user to take any part of another user's answer and use it to formulate a new answer or to edit an existing answer with it, without the original respondent's permission? If so, to what extent is cherry-picking allowed?

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_{¹ While Nathaniel inadvertently followed some of the Help Center's "How to reference material written by others" section, I do not believe Nathaniel's edit logically extends his own original answer in that the portion of LazyReader's answer he cherry-picked could be equally applied to everyone's answers for the same purpose. In other words, I believe he simply wanted to take what was the obvious Earth-biology example and include it in his own answer. I'm tempted to say that this isn't intrinsically part of my question here on meta, except that it represents IMO the worst-case example of someone cherry picking someone else's answer.}

Answer 1

The bottom line is that we're not here to compete with one another; we're here to write good answers (and ask good questions!).

I'm struggling to see where there's been any misconduct here. LazyReader's answer linked to the video, but prior to JBH's edit, it was rather tangential. The main point of the rather succinct first version was that tapuis involve a potentially relevant mechanism. The video itself was presented as an afterthought. Only after JBH's edit would I say it became an important component, and even then, tapuis are the focus of the answer.

There's nothing wrong with expanding on a point someone else has made. Collaborating is basically what we do. Taking someone's answer as a jumping-off point is totally fine - particularly if you credit them, as Nathaniel did. If someone thinks they can present an idea better than someone else, go for it. That's always been Stack Exchange policy. If you weren't allowed to do so, we'd have to delete probably a third of all of answers network-wide.

I think the comparisons to cheating on an exam or trying to get an advantage in a competition are misplaced. We're not playing a zero-sum game here. And it's not intellectual misconduct to agree with someone else's idea when it's kinda key to your own answer - Nathaniel opened his answer by postulating that it seemed unlikely, and indicating that that assumption might be wrong seems the right thing to do, ethically.