From an outsiders perspective it would seem pairing individuals (university and department heads) personal reputations in press with the sloppiness or unseriousness of the process would at least create some stakes for the decision makers no?
I've never witnessed straight corruption, but I did witness marketing teams sent to prey on researcher's fears. So I wouldn't discount that too.
When you go up for tenure, your publications are still fresh, so your impact is hard to know. So the rough rank of the journals in which you publish is a proxy for it. This is why universities reward publishing in some journals rather than in others.
Why do higher-ranked journals publish better studies? This may be for a number of reasons. Better studies are more likely to be submitted to higher-ranked journals first rather than to lower-ranked journals. Researchers who write better referee reports are more likely to accept requests to referee papers at those journals. And the editors may shepherd papers at such journals better too.
Notably, predatory journals do none of these. It is no surprise that publishing in predatory journals will not get you tenure nor promotion at such universities.
In Computational Linguistics (disclaimer: I'm a member of the ACL, the association that organizes the bigger conferences) you only pay the conference fee for at least one author to present your results. You pay ~$700 (students and virtual attendees pay less, but depends heavily on the location of the conference), your paper is published online for free, and you also get a conference out of it.
The main problem are Universities: when applying for a position, each University will rank you based on which conferences you've published. CL conferences used to be ranked lower than CL journals, so if you want to have a chance at tenure then you have to aim for the well-established ones. Why are they well-established? I can't say for sure but my best guess would be "look at all the marketing a $10k publication fee can buy".