Really? Creation of a judiciary was not one the proposed changes to the Articles. You contradict yourself. How would you have changed the Articles to incorporate a Judiciary, regulate commerce and provide for federal taxation? Unlike you, who has evaded answering these simple questions, our framers took on the tough issues rather than snipe at the accomplishments of better men.
Because, as I said, they already had a judicial function, without having a permanent judiciary. Note the mode of choosing judges. Quite interesting.
The United States in Congress assembled shall also be the last resort on appeal in all disputes and differences now subsisting or that hereafter may arise between two or more States concerning boundary, jurisdiction or any other causes whatever; which authority shall always be exercised in the manner following. Whenever the legislative or executive authority or lawful agent of any State in controversy with another shall present a petition to Congress stating the matter in question and praying for a hearing, notice thereof shall be given by order of Congress to the legislative or executive authority of the other State in controversy, and a day assigned for the appearance of the parties by their lawful agents, who shall then be directed to appoint by joint consent, commissioners or judges to constitute a court for hearing and determining the matter in question: but if they cannot agree, Congress shall name three persons out of each of the United States, and from the list of such persons each party shall alternately strike out one, the petitioners beginning, until the number shall be reduced to thirteen; and from that number not less than seven, nor more than nine names as Congress shall direct, shall in the presence of Congress be drawn out by lot, and the persons whose names shall be so drawn or any five of them, shall be commissioners or judges, to hear and finally determine the controversy, so always as a major part of the judges who shall hear the cause shall agree in the determination: and if either party shall neglect to attend at the day appointed, without showing reasons, which Congress shall judge sufficient, or being present shall refuse to strike, the Congress shall proceed to nominate three persons out of each State, and the secretary of Congress shall strike in behalf of such party absent or refusing; and the judgement and sentence of the court to be appointed, in the manner before prescribed, shall be final and conclusive; and if any of the parties shall refuse to submit to the authority of such court, or to appear or defend their claim or cause, the court shall nevertheless proceed to pronounce sentence, or judgement, which shall in like manner be final and decisive, the judgement or sentence and other proceedings being in either case transmitted to Congress, and lodged among the acts of Congress for the security of the parties concerned: provided that every commissioner, before he sits in judgement, shall take an oath to be administered by one of the judges of the supreme or superior court of the State, where the cause shall be tried, 'well and truly to hear and determine the matter in question, according to the best of his judgement, without favor, affection or hope of reward': provided also, that no State shall be deprived of territory for the benefit of the United States.