Why didn't Zheng choose?

I don't want strong people to inherit it.

Zheng's political idea is a country of Confucianism and ministers. He believes that the monarch should be moderate and inaction, and the government affairs of the country should be taken care of by scholar-officials who are proficient in Confucianism. Because of this political thought, Zheng did not want to choose a powerful person to inherit the throne, so he strongly recommended his youngest son, Li, who was weak by nature, as the prince.

Li Fangyuan successfully completed Daming's mission. Zhu Yuanzhang not only admired Li Fangyuan, but also became more and more famous in North Korea. Although Li Fangyuan made the greatest contribution and gained the highest reputation, when Li Chenggui chose the heir to the throne, Li Fangyuan was defeated.