You obviously don't trust Christ's words to Peter appointing him the rock on which the Church is based. There is nothing in the Vatican II documents that contradicts the deposit of faith.
That doesn't mean that there is automatically anything good or useful in the documents of Vatican II. All they need to do is confuse. Or as I wrote above provide the opportunity for sowing confusion.
Did Christ drop the ball or was it a good thing when Pope Stephan dug up Pope Formosus, put his corpse on trial, declared everything he ever did invalid, cut his fingers off that he'd used for blessings and dumped his body in a shallow grave, and a few days later threw it in the river?
Just because Christ has allowed human sludge and others of varying quality to occupy the chair of Peter and someone can recognize this, does not mean one has lost faith in the Papacy or Christ's promises. On the contrary, it indicates a person actually understands Christ's promises and the papacy and not the modern ultramontanist fantasies about the papacy.