Most of my arguments around peer-review being somehow “free” are laid out in this post:
From my perspective in the life-sciences, nearly 100% of reviewers earn a salary and reviewing is what one does if one wants to have one’s own papers reviewed: you can’t go around publishing in peer-reviewed journals and don’t contribute. That’s anti-social behavior. So as long as you publish in these venues, it goes without saying that you also review. If publishing is in your job description, so is reviewing, at least by extension. For my part, I review, because I consider it to be part of my job and I’d be anti-social if I wouldn’t do it.
So from that perspective, peer-review is not free. It’s paid labor, only that others are making a profit off of it. This is nothing new: tax payers pay public institutions, which in turn pay libraries to pay subscriptions or APCs: public money is converted into private profits along the entire pathway of science. There is no need to emphasize the review part: it’s just more of the same.
If, however, now something changes and not reviewing is not anti-social any more, perhaps because someone thinks it ought to be paid extra, then of course, there is little reason for me to keep reviewing: after all, someone is being paid for it (usually someone more in need of the moeny than me!) and it’s not anti-social any more to not review: no money - no work clearly isn’t anti-social, on the contrary: any review that I do, means someone more in need will have less food on the table. So by not reviewing, I’d even be helping the precariat out!
So, if reviewing gets paid extra and people think logically, everyone with a professorship stops reviewing and uses the time to write papers or do experiments or write grants, while everybody who can use a few extra bucks, e.g., ECRs takes time away from paper writing, paper reading and experimenting to review.
I think I do not have to elaborate any further that this is not where any sane person would want science to go, but give me one more scenario: in the US, scientists already receive only 9 months salary, as the university think they can get the remaining 3 months from grants. If reviews earn you money, why shouldn’t the universities decide to cut another three months for which you can do reviews?
So chances are, more likely than not, try to somehow compensate for peer-review and all kinds of detrimental effects start to happen.
There are some hilarious solutions such as taxing publishers for every word they get in subsidized reviews, but the best solution remains: we need to get a modern infrastructure where we control the amount of profit being made by actual competition. Short of that, everything else will just be a stop-gap or a patchy band-aid, and not a solution.