First, the Red Scarf Army lacked the spirit of unity, and the whole uprising was like a mess. Although there were only a lot of banners in red, and the number of people reached the peak at that time, none of these insurgents liked others, and the whole uprising was like a mess. Zhang Shicheng and Xu Shouhui in the south did not cooperate with the actions in the north, which eventually led to the internal disintegration of the rebel army.
Second, the insurgents have developed too fast and have not laid a solid foundation. At the end of Yuan Dynasty, the Red Scarf Army was an uprising with rapid development in history, which received the highest support and unprecedented personnel. It is precisely because of these that the insurgents have become a situation in which the outside is strong and the inside is weak. The rebels in the north have developed rapidly, but they can't win without that person's support.
Third, different religious beliefs are also one of the reasons for the failure. At that time, the rebels in the north believed in An Baili, while the men's army believed in Confucian classics, resulting in ideological disunity between the north and the south. There are many insurgents, but the most influential ones are the confederate army and the northern army. The Southern Army led by Zhu Yuanzhang saw the mutual killing between the Northern Army and the Yuan Army, and grasped this reality, thus occupying most of the southern regions and finally winning the war. Generally speaking, ideological disunity also accounts for a large part of the influencing factors.