The scriptures repeatedly mention the need for us to listen to the prophets, and they were not listened to, again repeatedly. Ether 11:22 is no exception. Each of the ancient scriptures ends with the society being destroyed after failing to heed the words of the prophet. In the Old Testament, the tribes of Israel were scattered, and Jerusalem was invaded. After the books of the New Testament were written, the Apostles were all killed. In the Book of Mormon, the Nephites were all killed, the Lamanites became depraved, and the Jaredites were also all killed.
Today, I know that Thomas S. Monson is our prophet, and I know it is best to listen to him, or else.