Sounds like the only benefit is keeping A in his delusion, instead of informing him via a competitive market that his skill is not as high as he thought he'd be. Oh, and saving the company money. And making it easier to have private favorites.

If someone is in an executive position, and something like you describe happens, it is their fucking job description to resolve the problem. Meanwhile, by having open salaries, everyone has the information needed for a competitive market. Including college graduates, who get screwed over routinely

//Edit: Oh, and if A ever DOES need to find a new job and advertises his "delusional" skills, either him or his next company will feel the pain from the lack of price information here