Why did the articles of confederation not grant the federal government enough powers

To prevent the government from becoming tyrannical.

Explanation:

The Articles of confederation was made by the founding fathers to specifically created a system of government that stray away form the tyrannical nature of Monarchy.

The founding fathers believe that if the power in the government is held by one king, there's nothing the people can really do if that King start abusing his power.

This is why the founding fathers did not granted the federal government enough power. They wanted the people to have every opportunity to overturn the government in case the federal government start abusing the power.