I think that's actually the danger here. I sympathize with you, but at the same time, I don't think it would add much value to just give a bunch of people the opportunity to air their grievances in job postings.
Having a feedback mechanism might encourage people to be nice, and I can't see how that's bad. Yeah it might suck to have to spend an extra two minutes talking to every candidate, but I don't see that making or breaking a company.
I suspect this sort of thing would be fairly rare, because it looks bad on both the applicant and the company.
(And no, I'm not excluding the possibility that I myself am one of them)
I'm not sure what goes through some of these companies' heads, but if they can't compensate adequately, then as a leader, I would not be able to assure employees that the company would be competitive hiring the best, unless the company had a particularly special angle such as being in the edtech space.