I tend not to believe the "no reason" part, but I still stand on their side when their privileges are revoked without human intervention and without a human customer support agent available by phone.
But think about it from the other perspective. Can they involve a human in every ban? Can they offer human support for appeals? You have nefarious actors with automated systems submitting malware and then automated appeals. How would Google or any other company cope with providing human support in every case?