...the guy who wrote that article seems very unprofessional to me

He's a highly respected statistician who's written some very valuable books, including at least one very useful book on teaching statistics. He actually says nothing about the rate at which he himself gives A's, just that all the incentives tend that way. In fact, at the end he cites an approach to post-hoc modification of grades which would make it irrelevant whether he assigned A's to everyone or not.