Who advocates that pen and ink should keep pace with the times?

Origin: Painter Shi Tao's "A Picture Book of Didazi's Poems and Postscripts" should change with the changes of the times and poetic environment.

"Pen and ink should change with the times, and the atmosphere of poetry should also change. Ancient paintings are simple and light, such as the sentences of Han, Wei and Six Dynasties. But the paintings in the Middle Ages are as magnificent as those in the early Tang Dynasty. Ancient paintings, like the sentences of the late Tang Dynasty, have become thinner. In the Yuan Dynasty, such as Ruan Ji and Wang Shen. Huang Ni's generation, like Tao Qian's words, lamented that beautiful women repeatedly bathed and fried with white water, and I am afraid it will never return. "

For the postscript of this painting, the current explanation is: pen and ink should change with the times, just as poetic atmosphere is easier ... If Ni Zan and Huang are still reciting poems, I'm afraid beautiful sentences are not good either.

This explanation seems to be very smooth, but it always ignores the description of ancient, middle and lower ancient paintings in the painting postscript intentionally or unintentionally, and delves into Tao Yuanming's poem "Worry about beauty hunter Bath, Self-defeating". "Pen and ink should follow the times" can be said to be a preconceived explanation.

However, as long as you read the phrase "ancient paintings" carefully, you can understand it as a footnote that "pen and ink should keep pace with the times and the atmosphere of poetry should change" Shi Tao believes that painting has gradually thinned from simplicity and significance in ancient times to grandeur in the Middle Ages. Obviously, this has nothing to do with the saying that pen and ink should follow the times.

Because the result of following is not as good as before. Why is this happening? The problem is that people naturally interpret the word "when" in "pen and ink should follow the times" as "should".