Fashion (which values novelty) is a major factor in web design, it stands to reason this preference would spill over to the underlying technical stack as well.
There is a web development culture. There was a pace of advancement for many years that helped shape this desire for newest shiniest stuff. Other ingredients such as chasing FAANG, VC money, and the general youth of the average web dev. Salaries chasing talent due to the online boom and corporate policies not adjusting to keep talent, thus needing to do resume building for the next job hop because it's going to happen in less than 2 years.