Why can Guan Yu and Zhang Fei, a vegetable seller, be a general?

After the worship of General Jintai, it was decided that the Zhou Dynasty would be the country of rivers and mountains after 800 years. Jiang Ziya is also a butcher. Having said that, let's review how Zhang Fei appeared in The Romance of the Three Kingdoms. He is eight feet long, with a leopard head, leopard eyes, a moustache, loud thunder and a galloping horse. Seeing his unusual appearance, Liu Bei asked his name. The man said, "A certain person's name is Zhang, and his character is also virtuous. Living in Zhuo Jun, I have quite a farm, selling wine and killing pigs, and making friends with heroes in the world. " This explains at least three points: first, Zhang Fei is burly and rough-looking. In the case of malnutrition among the general public at the end of Han Dynasty, the physical quality of a single animal was better than that of ordinary people. Second, Zhang Fei's family conditions are very good. At least he is a big landlord class, weak in literature and rich in martial arts. Third, Zhang Fei's "making friends with heroes in the world" shows that he is keen on making contributions.