This is going into alt history territory TBH. Keju was an improvement over the previous system which largely consisted of staffing the civil service based on an

This is going into alt history territory TBH. Keju was an improvement over the previous system which largely consisted of staffing the civil service based on ancestry from large aristocratic families who nominated each other to strengthen their political power. Imperial China's hegemony over its surrounding regions was not thoroughly challenged until the 19th century, and once it began to be challenged by nations with more advanced ideas and technologies, Keju did enter terminal decline along with the rest of the imperial system. Even without Keju, Early Modern China didn't have the recipes for scientific or industrial revolution to start there.