Well I think at least two men who became prophets disagree with you. Both JFS and HBL stated that the standard works are out canon and all doctrine is to be measured by them.
Chapter and verse please where JFS and HBL say that canonical things equal something other than between the covers of the "quad."
You seem to think the quad is little more then some doctine put in paper and that there is all sorts of stuff that is binding in addition to that. But the quad is the binding doctrine and measure what is or is ont binding.
The Enyclopedia of Mormonism declares
“Whenever new doctrines are to be introduced, they are first presented by the President to his counselors and then to the Quorum of the Twelve Apostles in a meeting of the council of the First Presidency and the Quorum of the Twelve Apostles. If unanimously approved, they are then presented to the membership of the Church at a general conference for a sustaining vote.” -- Encyclopedia of Mormonism, Vol.3.
B.H. Roberts has said “.
I do not think the world should require such perfection of us as to insist that our religious teachers always deliver the inerrant word of God! In any event it must be allowed by us that many unwise things were said in times past, even by prominent elders of the Church; things that were not in harmony with the doctrines of the Church; and that did not possess the value of Scripture, or anything like it; and it was not revelation. Moreover, no revelation even becomes the doctrine of the Church of Jesus Christ of Latter-day Saints until it is accepted by that Church by formal action; it must be accepted by official vote of the Church before it becomes the law of the Church (see B.H. Roberts, Defense of the Faith and the Saints, Vol. 2 p. 458).
Joseph Fielding Smith has written
“It makes no difference what is written or what anyone has said, if what has been said is in conflict with what the Lord has revealed, we can set it aside. My words, and the teaching of any other member of the Church, high or low, if they do not square with the revelations, we need not accept them. Let us have this matter clear. We have accepted the four standard works as the measuring yardsticks, or balances, by which we measure every man's doctrine. You cannot accept the books written by the authorities of the Church as standards in doctrine, only in so far as they accord with the revealed word in the standard works. Every man who writes is responsible, not the Church, for what he writes. If Joseph Fielding Smith writes something which is out of harmony with the revelations, then every member of the Church is duty bound to reject it. If he writes that which is in perfect harmony with the revealed word of the Lord, then it should be accepted (Joseph Fielding Smith, Answers to Gospel Questions, Vol.2, p.113-14).
More recently, in an area conference Harold B. Lee stated:
"If anyone, regardless of his position in the Church, were to advance a doctrine that is not substantiated by the standard Church works, meaning the Bible, the Book of Mormon, the Doctrine and Covenants, and the Pearl of Great Price, you may know that his statement is merely his private opinion. The only one authorized to bring forth any new doctrine is the President of the Church, who, when he does, will declare it as revelation from God, and it will be so accepted by the Council of the Twelve and sustained by the body of the Church. And if any man speak a doctrine which contradicts what is in the standard Church works, you may know by that same token that it is false and you are not bound to accept it as truth." (The First Area General Conference for Germany, Austria, Holland, Italy, Switzerland, France, Belgium, and Spain of the Church of Jesus Christ of Latter-day Saints, held in Munich Germany, August 24-26, 1973, with Reports and Discourses)
Understand now?