I've reviewed for some (high quality) Mathematics journals. Papers tend to be more complete, for sure, but the reviewing is much less rejectionist. I'm not aware of any Mathematics journal with a 10% acceptance rate, and even 20% is probably on the low end.
> It's an unfortunate reality of academia that there are fewer resources (jobs, grant funding, etc.) available, than there are researchers who are prepared to put them to good use.
I don't think this is true in CS. Universities outside of an elite set really struggle to hire and retain high quality faculty. It's at a crisis level outside of R1. Teaching-oriented institutions have mostly have stopped trying to hire traditional academics; a masters degree with some teaching experience is sufficient.
Some of this is due to industry -- high-quality faculty candidates tend to also have 3x-5x offers in industry, and it's hard to turn down a guaranteed early retirement for the grind and uncertainty of the tenure track. But I think some of it is also that students who would make good teachers and mentors lose confidence due to a series of unnecessary paper rejections and decide to nope out of academia.
Again, I spend a lot of time around academic mathematics. The rejectionist culture in CS is real. And not just conferences, btw. An NSF program manager started my last review panel by telling us that scores are consistently way lower in CS than in any other field and to please chill out.
That seems to just confirm that resources are lacking. There's no shortage of people, but there's a shortage of money to pay them.
Specifically, the 130 or so institutions listed here: https://en.wikipedia.org/wiki/List_of_research_universities_...
Heuristically, think "major private universities and flagship public universities".
It's an unfortunate reality of academia that there are fewer resources (jobs, grant funding, etc.) available, than there are researchers who are prepared to put them to good use.
Further, those who are making the decisions have limited time. If you're serving on a hiring committee and get hundreds of job applicants, you can't hope to read all the papers of all the applicants. To deeply read any one of them would take a fair bit of time.
We therefore need a signaling mechanism to distinguish the outstanding from the merely very good.
It's of course possible to argue about the details of how papers are rejected, as the authors indeed do. But unfortunately the core problem -- an aspiring academic will get rejected often, and it can be extremely demoralizing -- is one we probably can't solve.