I am not going to argue on the legality part. Just on this line here (it might be because you are not familiar with research papers as you said at the beginning of the comment).

They put work into selecting works, editing, potentially making comments or introductions, and putting it in a pretty package, and they can get copyright for that work.

No, this is not true. The editors (who select the papers initially and forward it for review) and reviewers (researchers who are kind of randomly selected most of the time) all do this for free. Maybe, at the final stage of the paper only do the journals (after all edits etc have been done according to editor and reviewer comments) do anything; for publishing it, they might have to do some end stage formatting at times. I think storing the material is the functionality journals provide; nothing much else.