> The distinction between HTML, JS and CSS always made perfect sense to me.

Really? HTML is already heavy on syntax, and the whole point of SGML-style angle-bracket markup is to invisibly structure text hierarchically and sneak in rendering properties or other "metadata" not rendered to the user, via attributes. In which universe, then, has it ever made sense to write

    <div style="color: red">

rather than

    <div color=red>

in a document representation language? Let alone today's CSS atrocities. Mind, I'm not talking about CSS' out-of-control layout model complexity, but inventing a new syntax (or a thousand microsyntaxes really) on top of already syntax-heavy markup.

If you think about it, CSS appears to have gotten these ninja super-powers because HTML was locked in a decade-long stagnation while W3C was busy with XML, RDF, and whatnot. Then again, in the last decade using <div>s for nearly everything was frowned upon, so with the precedent set in the decade before, CSS just had to re-order, re-place, re-arrange ad absurdum without any discernible mental discipline. Or, maybe the CSS WG people just couldn't stop.

The end effect is that CSS isn't approachable for even seasoned graphic artists let alone laymen; another effect being browser complexity resulting in monopolies.

A false separation-of-concerns narrative has ruined many languages and approaches (such as enterprise OOP); for the web it was particularly idiotic given it's founded on composable documents.

JS? Once it was out there, evolution of HTML and declarative UIs basically stalled because there wasn't anything you couldn't do using JS. Nevertheless, CSS had also grown into outlandish complexity. Basically, the "web stack" of today is what any standardization effort should've avoided.