This is the reason that Moroni included this story. Perhaps there were so few stories that he included every story that Ether had recorded, but the meaning of this story assured that it would be included. This is the story that caused Mormon to desire that the Jaredite story be ultimately told. This is the story that Mormon did not want told widely so that the secret combinations would not be continued.
To make sure that we get the message, Moroni warns us that “the Lord worketh not in secret combinations.” This is not of God, but of the Adversary.