This is really a funny statement by the author...stated as if it wasn't St. Peter's Basilica personal fund-raisers like Tetzel weren't behind how these "common folk" "came away" "with erroneous ideas."
'Twas the false prophets of Rome who were leading them astray like a pied piper!!!
Johann Tetzel: "You should know that all who confess and in penance put alms into the coffer according to the counsel of the confessor, will obtain complete remission of all their sins...Don't you hear the voices of your wailing dead parents and others who say, 'Have mercy upon me, have mercy upon me, because we are in severe punishment and pain. From this you could redeem us with a small alms and yet you do not want to do so.' Open your ears as the father says to the son and the mother to the daughter . . ., 'We have created you, fed you, cared for you, and left you our temporal goods. Why then are you so cruel and harsh that you do not want to save us, though it only takes a little? You let us lie in flames so that we only slowly come to the promised glory.' You may have letters which let you have, once in life and in the hour of death . . . full remission of the punishment which belongs to sin..."
See pp. 78-79 of The Role of Indulgences in the Building of New Saint Peter’s Basilica
This is no longer the case with indulgences.