HTMX deals with loading content into the DOM, not managing display of the DOM.
They serve two different roles and together should handle the majority of javascript framework use cases.
Web Components does cover some of the same use case as HTMX, but is intended for when a server is returning data rather than HTML. It is both more powerful and more complex.
> the specific example of just having a search box autocomplete can actually be fulfilled with a datalist element. It won't dynamically re-query results, but it will filter based on input. So it's a muddy example, at best, and that's probably not great for the point trying to be made.
A prefilled list is never an acceptable solution for a search box. A search box is meant to capture arbitrary input. A filterable datalist is not a search box.
