Aesthetically speaking, in addition to whether something is beautiful or not, whether it can be reproduced often affects the judgment of beauty.
So in addition to the beauty of ancient things, another important factor is that they are difficult to reproduce. At the same time, as time goes by, it becomes more and more precious.
In addition to works of art, people actually like Shigu in many aspects and think that the previous things must be better. Therefore, Confucius always wanted to restore etiquette, so people often say that people's hearts are not ancient.
But history is always changing. If you have read "A Brief History of Humanity", there is a chapter dedicated to this, but it is not an authoritative opinion. The author believes that before the scientific revolution, people were generally superstitious about history because they could not admit their ignorance, and history can often be known, so better things can often be found in history. But after the scientific revolution, people began to realize their ignorance and began to look to the future for answers.
So the saying that calligraphy is difficult to compare with the ancients should have its reasons (for example, the history of art often jumps, or the talent is unprecedented and unprecedented), but there is also the inertia of historical aesthetics in it.