Answer: To avoid creating another monarchy or something like it.
Step-by-step explanation:
After independence was won from the British, the new American nation of the United States of America did not want a situation where the British system of government would be reciprocated as they felt that it would just lead to another round of abuse and exploitation.
They therefore did not include the position of a President or central ruler in the Articles of Confederation. This was reversed in the Constitution when it was realized that a strong central figure was needed to rule.