[southerntofu]

The problem is the declarativeness of the web is very much limited for UI/UX purposes. There's been good steps taken with HTML5, although dropping XML-compliance was in my view a major mistake in terms of operability/simplicity.

I don't understand why we need to have dozens of CSS frameworks for "components" that have become common practice across the ecosystem. Pagination, "Hero" elements, intra-page tabs, breadcrumbs (and many others) should be HTML standard so that it's more accessible and users can come up with their own stylesheets. The breadcrumbs for example would enable your browser UI to show a "go up" button like your file browser does. Another interesting example would be element filtering: why can't a <form> with a local action property (like "#data") be used to filter a list of elements without JS?

As long as most UI of a page is dictated by dozens of piled-upon CSS hacks, user stylesheets will remain a wild dream. But given how little variety there is on the web these days, many things could be standardized part of the HTML spec so that CSS is only needed for customization (eg. colors, spacing) on simpler pages, while retaining the possibility for the server to suggest more complex CSS UIs as we currently do if you absolutely want to do that.