Because Zhong Yao’s regular script requires very strong basic skills, which most people cannot master.
Zhong Yao’s position in the history of calligraphy:
First, the originator of regular script. Zhong Yao was a famous calligrapher and politician from the late Han Dynasty to the Cao Wei Dynasty of the Three Kingdoms. He was good at seal script, official script, Zhen script, Xing script and Cao script. He was quite accomplished in calligraphy and promoted the development of regular script. He was revered as the "originator of regular script" by later generations.
Second, as famous as Wang Xizhi. The sage of calligraphy, Wang Xizhi, was greatly influenced by him. Zhong Yao had a profound influence on later generations of calligraphy. Wang Xizhi and others once devoted themselves to studying his calligraphy, and he was called the "King of Zhong" together with Wang Xizhi, a calligrapher of the Eastern Jin Dynasty. In a sense, Zhong Yao is Wang Xizhi's teacher.
Thirdly, Zhong Yao's calligraphy is called "divine quality". The main works handed down from generation to generation include "He Jie Biao", "Li and Fate Table", "Declaration Table", "Recommended Ji Zhi Biao", etc. Yu Jianwu of the Southern Dynasty ranked Zhong Yao's calligraphy as "top grade", and Zhang Huaiguan of the Tang Dynasty listed it in "Book Break" Zhongze commented on his calligraphy as "superior". It is unique in the history of calligraphy that can be called "divine".
Difficulties of Zhong Yao’s regular script:
Practicing Zhong Yao’s regular script requires profound basic skills. If the basic skills are not solid, you can only practice Zhong Yao’s small regular script directly. In painting and writing, there is very little "writing" involved, and most of it is "drawing", which means it is difficult to use the pen fluently when copying. Especially if you don't understand the coherence and fluency between Zhong Yao's regular script strokes, you can basically just "draw characters".