Actually, he was human and, thus, not perfect.
What he accomplished was Herculean, but all men are prone to error...even Luther.
Of course no one has said anything about perfection. And I note that that rabbit trail skirts the matter of a corrupted Christology produced from demeaning the Blessed Virgin.
what he accomplished was a MAJOR disaster...he could possibly be the direct cause of more people to lose their souls than any other person in history...he led literally millions of people away from the true church of Christ.