Do the publishers (somehow) force the authors to give them exclusive publishing rights or something? If not, why are these authors simply not putting their papers on multiple journal/platforms?
2. Back when I published this paper, there is little if any discussion of such issues in the Biology community. It just did not occur to me that this would be an issue.
3. Some journals allow one to post preprint versions of papers on preprint servers. In some fields (math and physics) this is common. In others (e.g., biology) this is rare. But we know do this and there are efforts (e.g., BioRXiv) to make this more common.
However, this is not a barrier to including papers in institutional repositories etc, simply to publishing in multiple journals.
Whenever I've been published, I've asked to retain copyright and that has been granted -- I'm not sure it's a grant, though, since it's mine to start with. The usual negotiating starting point is a contact from a publisher that automatically claims copyright. I simply delete that clause (and possibly insert "The author retains copyright", so that there's no doubt).
Clearly, that's not happening here and I don't understand why, unless publishers are refusing to publish without being given copyright. In which case, alarm bells should be ringing very loudly.
So only dodgy journals will re-publish work that has been published elsewhere.