Granted, the current journal publishers spend too much money on overhead, and I certainly don't support the for-profit ones like Elsevier that rake in huge profits. But I also don't see much allowance made for the fact that publishing research in a peer-reviewed format involves labor which should continue to be compensated in some way (incidentally, it's not entirely true that researchers themselves aren't compensated - publishing offers an indirect benefit but a real one in the sense that publications are directly linked to salary increases down the line).
Peer review is done by others in the field (peers), typically for free. Online publication is "where do I stick this PDF", and does not require per-paper work (or if it does that can be done by the author). That leaves us with copyediting, and in many cases, copyediting issues are caught by peer review rather than any paid editor.
I also think that you underestimate the importance of copy-editors. It's not the job of a peer reviewer to make sure that the author uses an apostrophe properly, etc. There needs to be a specialist who is dedicated to catching those errors, particularly since, as you note, peer-reviewers aren't directly compensated so it's unfair to burden them with a whole other set of responsibilities.
Many Elsevier and Springer journals no longer perform copy-editing. Authors are expected to have their paper checked by a native English speaker and copy-edited at their own expense, and then provide the journal with a camera-ready PDF. In my own field, it is the open-access journals published by non-profits that actually have the best language quality and typesetting.
This is a problem that goes beyond journals into for-profit scholarly publishing more generally. In my field, Brill is an infamous publisher for this: it demands camera-ready PDFs for most of the monographs it puts out. So, your library ends up having to spend 400€ on a book where about all the publisher contributed – besides unpaid peer review – is printing, binding, and mailing it out.
I think "needs" might be too strong here. We (the field of CS) get by without it just fine -- the standard practice is to include copy-editing "nits" at the end of one's review. A shepherd, assigned during the final phase, does a final pass on the paper before approving it.
Yup. Typos slip through. There are papers with poor English. Oh well. For the most part, it works out pretty well.
(And as a reviewer, I have little objection to also noting writing fixes while I'm reading your paper. I'm going to spend anywhere from 30 minutes to 5 hours reading the thing -- the writing fixes are a small additional cost. If you've done a decent job on the writing in the first place. If it's totally botched, I'll reject your paper and tell you to fix it before submitting it again. :-)
Now, would I prefer that the authors of submitted papers had to pay $50 for someone to do a copy-editing pass before I reviewed it? Heck yes. But perhaps we'll get DNNs to fix this for us one of these days. :)
Likewise, it's normal for editors in my field to make meta-level suggestions about writing style. I'd wager that history journals place a greater emphasis on prose style than CS journals do, since making an historical argument often depends on telling a compelling narrative. Hence a publishing model that works for a CS journal might not work for humanities journals and vice versa.
Maybe I gave the wrong impression by mentioning apostrophes, however. Professional copy editing is, in my view, super important in terms of differentiating a good journal from a bad or mediocre journal. As is the vetting procedure of finding appropriate peer reviewers and coordination between them. Whether or not you think of that as "real" work compared to producing actual research, it is still work that should be compensated in some way, in my view.
An analogy might be the professor teaching a class vs the maintenance guys who makes sure the projectors are working and the lights turn on. One might be more important than the other, but I don't think either should be working for free.
I'm confused that you aren't aware of this but, peer review and copy-editing is by-and-large done by other academics, not journal publishers, and, at most, for what amounts to an honorarium.
And online publication is not a job, per se. We automated it a long time ago. Teenages have tumblr blogs now. There is no reason why the practical aspects of online journal curation could not be handled by a very small team of people working in the IT departments of a few universities.
Journal article publication may contribute to academic careers, but that has nothing to do with the publishers' involvement: it has to do with the quality of the journal, which is driven by the academics in writing and reviewing for it.
Simply put, journal publishers are >entirely< overhead.
And although peer review relies on specialists volunteering their time, finding and vetting those specialists still requires work.
I'm not trying to say that the current publishing model is defensible, but I am pointing out that running a high quality peer reviewed journal still requires at least one or two dedicated workers. Whether you think they should be paid for their time or expected to volunteer is a different issue, but we shouldn't pretend that the whole apparatus is an illusion created by greedy publishers.
Also, no editor at any journal (I've published ~20 papers) made any edits to my papers.
If the editor sent some copy edits to the text, I'd just send it back to them unedited and ask them to publish it. In fact, I love pushing back against unreasonable editorial requests.
The other day in a HN discussion, someone cited a paper in response to my comment. I was able, in 30 seconds, get to the full text of that paper, which allowed me to reevaluate my opinion in context of what I read.
This is how science can, and should be useful for individuals. And beyond arXiv and SciHub, it generally isn't.