Why can't the ancients send poems to their parents?

Throughout the ages, poems written by the ancients, such as appreciating, responding, expressing feelings and chanting things, are invisible. Why? According to ancient etiquette, father and son can't stand side by side, and they should talk about their position when eating at the same table. As a short poem, it is not polite for children to send one to their parents. Therefore, Pan Yue wrote many mourning poems just to mourn his wife. Ouyang Xiu wanted to pay homage to his mother, but he couldn't express it in poetry. He just wrote a long "Long Steel Clamp Watch". Wu Jiaji, a poor poet in Qing Dynasty, wrote a poem "Selling Books in Memory of Mother" in memory of his mother, which was only a chronicle, but this passage was not given to his mother. At the same time, apart from the reasons of etiquette, poetry is characterized by being short and pithy, and paying attention to subtlety and euphemism. It is lyrical, and it is not reasonable to communicate with the immediate elders in a roundabout way. Similarly, there are no lyrics or songs for parents. Later, songs and songs appeared, which are variations of poetry, and of course they also inherited the taboo of writing poetry. Of course, the ancients could not give poems to their parents, also because poems pay attention to expressing their feelings directly. Who would set the etiquette in such a short chapter? (Han Hui)