I assume that you mean the denial of the many things that the RCC has concocted about her that are not at all in the bible. I don't have a lot of concern about believing things that are not in the bible.
This is from the ending of the Gospel of John. Because of this, it would seem that the Gospel is "incomplete." If some of these things were deemed important by the early Church, but wasn't found in the written Scripture (remember the Church came first), who passed them on?