But the chance of a web page actually needing that functionality to render at all is rare for hopefully-obvious reasons. The status quo is that progressive enhancement is dead: a few-year old copy of Safari can now simply not browse much of the web anymore because it is missing some corner case of CSS or web components or whatever: I often am stuck at loading spinners or are simply thrown into a blank page... the best case is a client-side rendered 500 error on many pages.

It was critical for the web to be easy to implement the core of for a small team or even a single concerted god-tier developer--imagine Fabrice Ballard--and the current spec has failed so hard at this that even tech megacorps have thrown in the towel. People get upset about WebUSB... but that's not the API surface that is causing us issues. If I had to single-handedly implement all of canvas/WebGL/WebGPU and JavaScript/WebAssembly I could pull it off (noting I used to be a video game engine developer).