Compared with Sanmenxia, what are the advantages of Dujiangyan ancient water conservancy project? Why can't modern man-made engineering have the level of the ancients?

Ancient people did not have modern technology, so they could only accumulate experience through constant practice. Secondly, the ancient people had a strong concept of loyalty to the monarch and the people, and they were very involved in water conservancy projects related to the national economy and people's livelihood. Modern people have technology, few people practice it, and few people serve the country. It's only temporary, not long-term.