“Protestant groups display a wide variety of different doctrines. However, virtually all claim to believe in the teachings of sola scriptura (”by Scripture alone”—the idea that we must use only the Bible when forming our theology)”
To believe otherwise is to confer genuiness (is that even a word) on things like the “Book of Mormon.”
That isn't true - the Church teaches "by the Teachings of Christ and the Apostles alone," so to speak. We include Sacred Tradition with Sacred Scripture, both sides of the same coin - the Oral teachings and the Written teachings. The Book of Mormon is an attempt to create new Scripture, while Tradition is unbroken since the time of the Apostles.