That kind of behavior is what has ruined most social media. The job post threads are great because they are strictly about job posts. They would be much worse if they also included random color commentary. Everyone using this site knows how to research a company. There is literally no upside and a huge downside to what you're advocating.

I can see how allowing this could discourage companies from posting in these threads. I think it would be interesting to see how a hiring thread including criticism would play out, but appreciate that it would also likely invite a lot of flame wars, astroturfing and unproductive bickering.

A (different) jobs board where the companies posting the jobs do not have control of the comment discussion would be interesting to see - but would need a monetization strategy that ensures it can survive without turning into pay-to-censor junky platforms like Yelp or Glassdoor.