BoM says of itself it is comparable to the Bible and contains the fulness of the everlasting gospel. Why is not Mormon doctrine taught in the BoM?

Many people assume that if they read the Book of Mormon they will get a good idea of LDS beliefs. However, the Book of Mormon teaches one God, not plural gods as in Mormonism. It mentions heaven and hell, not three degrees of glory. There are no temple marriage or secret temple ceremonies. It does not teach baptism for the dead, pre-existence of man or eternal progression and other ordinances. If the Book of Mormon is a restoration and another Testament of Jesus Christ, why are not these teachings in the Book of Mormon? Afterall, Joseph Smith said, "The Book of Mormon is "the most correct of any book on earth." (History of the Church, 4:461.) For the sake of clarity I will add the following site which explains all about ordinances in detail. Please note that at the end there are references given by the writer of the article. There is not one reference of any of these ordinances taught in the BoM. https://rsc.byu.edu/salvation-christ-comparative-christian-views/role-ordinances-church-jesus-christ-latter-day-saints