The emperor was in danger of the empire created by the Clone Wars project. He was concerned about the limits of centralization. The Clone Wars boldly transformed the social structure of the entire galaxy. At that time, many republican citizens supported a centralized system, which was also a justification for the cause of the Clone Wars led by Palpatine. An excessive and tough system was realized in just three years.
The Galactic Empire under this system was a mechanism that consisted of Palpatine, who was crowned the emperor, living and taking control of everything. However, it was a concern that one mistake of the emperor would put the empire in crisis. As long as the emperor is human, the chances of making a mistake are not zero. Here is the root of the divide and rule.
The emperor, who has been advised by scholars and senior officials who warn against the harmful effects of centralization, makes Exegol an empire insurance. Considering that the collapse of the empire is inevitable, the emperor plans to deceive the galaxy again.
The centralized system does not deceive the galaxy again, disguising the death of the dictator and calming the galaxy.
Even the generation tired of the Clone Wars is deceived.
Due to the great success of the Clone Wars project, citizens throughout the galaxy regarded the emperor during his lifetime as a man of thorough centralized governance and dictatorship. He never thought he would do a decentralized dictatorship behind the scenes after his death. The emperor was transforming.
By decentralizing him, it is possible to reduce the burden on the dictator. The emperor himself was worried about the exhaustion and burden of his empire. He should have strengthened his authority over the staff in a position like Mofu of the Empire.
First Order does not have a centralized mechanism to prevent its presence in the New Republic. The Resistance doesn't know the whole story of the First Order. Since it is smaller than the empire, there is no guarantee that you will win if it becomes a war head-on, so the Cold War structure is good.
The aim was also to allow the Sith Eternal to function in the Divide and Rule in case the Emperor's rebirth fails.