HTML in JavaScript still feels wrong to me and I still hate JSX. The Vue and Svelte approach to simply having the HTML in the same file was much more digestible.

I think React won because it had a more gradual learning curve than Angular and a didn’t drastically change between versions.

And the idea that HTML/CSS/JS are non-isolated is over-thinking it. It only applies to the world of Webapps. HTML can be published and served all day without CSS or JavaScript. And you can do a lot with HTML and CSS alone.