These things, while beneficial, don't owe their existence to CSS. Instead, introducing eg. CSS shapes or `content: ` (as two extreme examples) was the way of least resistance/guerilla tactics, as opposed to putting the functionality into SVG proper, or aligning the layout box model better with the DOM model, resp. Now what we're left with is a way overcomplicated mess for generations to clean up. There's a reason Mozilla spent the better part of the decade to come up with a new web renderer.

Don't get me wrong. I praise CSS for it has given designers ways to come up with new UI idioms (something I'm personally fascinated with). But I will say this has happened in spite of, rather than because of, CSS's qualities. Designers other than outright CSS nerds are struggling with CSS, and CSS is lacking badly from a basic maintainability perspective IMHO. CSS as a language puts an unnecessarily high cognitive burden on casual web developers by lacking a construct to capture the "intent" of a couple coordinated CSS rules; as a result, unless you're doing CSS every day, you're easily lost in your (or someone else's) CSS.

This isn't helped by seemingly arbitrary decisions as to what goes into CSS vs. HTML. For example, responsive images eg. the `picture` element became an HTML element, but arguably should have been subject to CSS media queries instead.

Which is kindof my initial point: that the HTML/CSS dichotomy is accidental and pointless from a language theory PoV.