In my experience, remaining employees generally understand what happened without the company having to disclose exact reasonings. Especially publicly.

Employers airing dirty laundry is way worse for morale. Typically the people who work in close proximity have a good idea of why their colleague may have been fired, or can reach out to them privately to get details. If the fired employee doesn't want to talk about it, it's presumably something private, and the employer probably shouldn't either.