You also give way too much credit to the “outsiders”. Vatican II’s issues was more of an internal problem.
Simple fact is there was much input from protestants during Vatican II. And after the council, even though hardly anything of note came out of it, little by little protestantism started creeping into the Church. Communion on the hand, altar girls, ridiculous hippy guitar playing at Mass, commune-hippy holding hands during the Our Father. Too much noise in the Church, the lack of reference, doing away with communion rails. The list is endless. And none of this came out of Vatican II. It was the atmosphere created out of Vatican II that allowed this to happen. And not enough bishops put their foot down and stopped the nonsense. And lastly, the acceptance of men with strong homosexual tendencies into the priesthood. Once again official Church teaching didn’t change, it was the seminaries letting these homosexuals in. Now that would not be that bad if the average homosexual man could remain celibate, but studies have shown time and again, most homosexual men are predators. For a time they can keep their sexual desires until control, but it eventually rears it’s ugly head. 90% of the sexual abuse cases in the Catholic Church are from homosexual men abusing young teenage boys. And this was made possible by the permissive attitude created by Vatican II.