I wish this would work but it won’t. They’ll just get shittier reviewers who’re willing to do it. ImmigrNt researchers use reviews as evidence of expertise so there’s at least one group of folk who are incentivized to review for anyone.
Yes, there is a career incentive to review, but it's much weaker than the one to publish, and comes later in career, so hopefully more people can afford it.
And yes, there will probably always be people willing to do reviews for free. But if the quality/delay/expertise of reviews from commercial publishers starts to degrade, it encourages authors to look for alternatives.
The issue is as a semi disingenuous researcher (which honestly most are) you actually want reviewers who are not experts because they won’t ask the hard questions and do a thorough review. So if you can get your nat neur submission reviewed by a bunch of desperate postdocs aiming to please then you’re hitting jackpot.
True, but academic journals usually try to maintain some sort of acceptance ratio, and avoid accepting every submitted article. (If they do, they will have the reputation of not being selective, which will harm their rankings and will make people try submitting their work to more selective venues first.)
Of course, for commercial publishers, there is an incentive to publish more -- so there is tension between taking more articles (more revenue in APCs, more volume, easier to attract subscriptions, more perceived impact for extensive properties like h-index) and being more selective (more prestige).
So worse reviews probably doesn't mean more papers accepted but a more random selection of accepted articles.
Assuming that articles have some intrinsic "quality" that most researchers would agree on, and that good reviews are better correlated to this quality than bad reviews, one would expect that getting worse reviews would make the journal selection process (even) more noisy. This can harm the prestige of commercial journals (if they start rejecting articles perceived as "good" and publish articles perceived as "bad").
I also have an initiative to boycott reviewing for closed-access journals with currently >350 signers. If you agree, consider signing it :) https://nofreeviewnoreview.org/
Indeed, for-profit publishing only works because researchers are willing to do free reviewing work for such publishers.