Traditional Wushu completely defeated the fighters.

Your equation doesn't hold. The advantage of traditional Wushu lies in keeping fit and cultivating temperament, not fighting. The so-called old Sanda does not practice, and less martial arts does not practice. Compared with combat effectiveness, I personally think that modern fighting is indeed superior to traditional martial arts. However, this does not mean that a modern boxer must have an ancient martial arts champion. People have different levels. No one knows if they haven't played. Moreover, the fist method of Wu Zhuangyuan is only secondary, and weapons, riding and art of war are the main objects of investigation, which can't beat the Sanda champion and Muay Thai king you mentioned.