When it's shown that there are significant historical problems with something like the perpetual virginity of Mary, her assumption, or praying to saints (e.g., the early absence of the belief, early sources contradicting it, sources being agnostic about it as late as the medieval era), a common response is to say that all apostolic churches accept the belief in question. Or we'll be told that some or all of the foremost leaders of the Reformation accepted it, that early Protestants in general did, or something else along those lines. We'll be told about how all of the apostolic churches practice prayer to the saints, how high of a Mariology the leaders of the Reformation had, and so on.
Several things need to be kept in mind when that sort of response comes up:
