Why is oracle calligraphy mediocre?

The Oracle Bone Inscriptions of He Group has a great span in time, extending from the second period of the fifth period to the fourth period, while the unnamed group is equivalent to the second half of the second period of the fifth period to the fourth period. The works of this period are not novel and gratifying, mostly small-print works, or neat or slightly sloppy, and the big characters are slightly sparse. It can be said that oracle calligraphy in this period is relatively mediocre.