Even after all that, you still haven't made explicit the thing that needs to be explicit for any of this to make any sense:
".... for UI *IN A BROWSER*"
I know it's convenient to forget the millions of us who spent years and continue to spend hours implementing UIs outside of a browser context, but it certainly doesn't feel very polite.
2. Even in the browser it's the worst possible system
3. The original comment I was replying to didn't make any references to "in the browser", and explicitly talked about things like QML and XIB which are very much not in the browser.
I don't think anyone's trying to be impolite or diminish What Came Before, but HTML is used for lots more than websites and browsers. (Examples that come to mind are email, desktop and mobile apps, ebooks, and digital signage.)
Yes. Unfortunately we've not inly settled for one of the worst systems, but we additionally further settled for limited subsets of it as well (email, ebooks)
