> In web development, Hydration is a technique to add interactivity to server-rendered HTML. It’s a technique in which client-side JavaScript converts a static HTML web page into a dynamic web page by attaching event handlers to the HTML elements.

This is how I use JS. I may be misunderstanding something, but this is a nice way to use JS to add targeted interactivity to a page while keeping load times and interaction-latency low. Modern JS is good enough for this purpose without the webpack/VDOM/bundling/dependencies that have made many websites sluggish.