Well, one thing I can think of which happened in the 19th century was the Protestant movement as a whole trended away from reverence towards Mary, which they had retained for centuries after the split from the Catholic Church. In Protestant America, so long divorced from the culture of Europe, the reverence towards Mary began to feel alien to the fundamentals of the faith, and so the reverence of Mary became “Mariolatry” in the rhetoric of hot-headed preachers.
Surely, the original Protestant leaders excised much about Mary from their doctrines, but yet they did honor her as the Mother of God, eternal virgin and exemplar of the Christian faith.
The protestants had no need to declare themselves sole guard of faith, unlike the corrupt Pope who delared himself free from error in faith and morals, after he lost his temporal power over the Papal States. (having proven him self not free from error in miltary matters)