> Reactivity is updating the DOM whenever the underlying data is updated. That's one of the most basic reason for existence of all js frameworks.

Most web apps and websites do not have that much state variables (even though it may be a lot of data). So while React may offer a small dev speed boost, it’s consumed by the need to build stuff and a whole deploy pipeline to nurse.

Libraries like HTMX and Alpine can take care of most the boilerplate for old style imperative patterns. And backend frameworks like Rails, Phoenix, Laravel donhave their own implementation for data updates.