Congratulations to the New Three Kingdoms. Dad can be the emperor. What is the punch line?

This sentence shows the childishness of the screenwriter.

Being an emperor is a very complicated system engineering. Possession of the imperial seal is only one of the most insignificant conditions.

As an official's son, Sun Ce should have a full understanding of the difficulty and complexity of calling himself emperor. The screenwriter designed such a line here, which made Sun Ce look silly. So many people laugh, not at Sun Ce, but at the screenwriter.