The idea is to cause those individuals not in full Communion with The Catholic Church to wonder is "Sola Scritpura" really true and to wonder if Christ really preached unity why there are so many denominations.
Did not Christ also prophesy that many would come on the basis of his name and many merely claiming to be his followers?
Jesus did give a means of determining who was in unity with him and thus enjoy internal unity also.
When the RCC returns to God through faith in Christ, it might have an opportunity to lead more believers. Until that time, while many members of the RCC are also members of the Catholic Church, the RCC falls short of the Catholic Church.