> any reason it couldn’t have mutated to have 2 hearts servicing each side of the body

There are probably no hard reasons. It is most likely that the path of incremental changes leading to that solution is either unlikely, or does not convey an advantage to propagation of genes.

> Did I miss something?

Probably. Planb’s message suggest that the first paragraph is their own writing, the second paragraph tells us that the third paragraph is the llm “improved” version of the first.

> If they had direct evidence that some author's instructions failed to ask for the case study to be fictionalized, I think they would have specifically said that.

Which they do. They specifically say that. “Neither the instructions for authors from 2010 — when Koren and his coauthor Michael Rieder would have written their article — nor the linked list of article types — state the cases are fictionalized, or fictional.”

“An archived version from September stated, ‘Each highlight is a teaching tool that presents a short clinical example, from one of the studies or one-time surveys,’ with no mention of fiction.”

These are direct quotes from the article. The exact kind you are asking for. With inline links to the archived documents. And yes it is very definitive.

> I'm pretty sure what happened here is that:

No need to speculate. Just read the article.

> 1) The journal always asked for […] fictionalized case studies.

This is false. As evidenced by the article.

You will have a long trek to do that. We have a javascript interpreter deployed at the second Sun-Earth Lagrange point.

https://www.theverge.com/2022/8/18/23206110/james-webb-space...

They asked the authors for fiction “at times”. Meaning that some are fiction, and some very well might not be. The best they can do is try to contact the authors and see if the case report they wrote is fictional or not. The second best is to admit that they made a mess and say “the case reports might or might not be fictional, we have no way of knowing”.