For the graces of indulgences are concerned only with the penalties of sacramental satisfaction established by man.*
If the church is making rules about consequences for sin, then it is able to establish a system todo away with those consequences, but not before God.
Only God can deal with eternal matters, and a system that would look for satisfaction outside at Jesus is wildly mistaken.
This is not dissimilar from a government imposing fines to make some wrongdoing settled. But paying that fine does nothy about the sin before God.
