The Buddha and Nichiren taught Three Treasures and Three Great Secret Laws. They also taught that the Treasure of the Law and the Secret Law of Namu Myoho renge kyo reigns supreme among all the treasures and secret storehouses of the Buddha..
Picture the Gohonzon as a human being. Namu Myoho renge kyo is the brain and spinal cord [central nervous system]. Although the brain and spinal cord is the master organ that controls all the other organs, in order to perform properly and harmoniously, a person needs a heart. Lord Shakya of the Original Doctrine is the heart of the Gohonzon.
Removing Lord Shakya of the Original Doctrine from the Gohonzon is like a person without a heart. A father whose heart dies loses his ability to support his family. The Nichikan and Nichiren Shoshu Gohonzon are Gohonzon in which the heart is destroyed. They can benefit no one.