Why were the American Articles of Confederation ineffective?
The Articles were founded on the philosophy of Rousseau which didn't work.
The Articles did not have an executive branch. The colonists feared the power of the executive after their experiences with the king of England. The fear was that a president would become a king an absolute ruler ignoring the wishes of the people.
The Articles did not have a judicial branch. The judges were state judges. There was no way to judge disputes between states. The Articles depended on the good will and honesty of the states in disputes with other states. This was in line with Rousseau philosophy of the innate goodness of human kind.
The legislative branch also depended on the good will of people. The laws had to be approved by 9 of the 13 states. The idea was that the legislators would do what was best for the nation and the entire people of the nation. Instead the legislators voted for the self interest of their state and this resulted in a stale mate were little could be accomplished.
The central government had no authority to tax and was dependent on the "good will" of the states honoring requests from the central government. The central government did not have money to fund an army, navy and had trouble running even the post office.
The Enlightenment philosophy of Rousseau failed to work as the basis for running a nation. The Articles of Confederation were formulated in 1778. They were ratified in 1781 and repealed in 1789. The articles did not serve as a lasting basis for the government of a nation.