This is probably coming to CSS in the coming years. [0] Which makes me very excited for one reason: CSS is nearing feature parity (and surpassing it in some areas) with Adobe InDesign, so we can finally ditch adobe and just make print publications within the browser. The only other thing missing after custom colour profiles is a proper text justification algorithm, although, for many, it's not so important because people are already used to reading ragged text.

[0]: https://www.w3.org/TR/css-color-4/#color-space

It's in the CSS Color 5 spec - here: https://drafts.csswg.org/css-color-5/#cal-cmyk

I don't understand how this is still a thing in 2024.

It’s essential complexity, so it’s not going anywhere.