A lot of it is about text, I guess!
Once you've re-implemented all that in a canvas, you've more or less built another web browser, so why not just use HTML?
I agree that it would be kind of silly to then put this in the browser. Instead, I think it could be used to build the native target.
And just to clarify my earlier statement, I'm not a fan of phasing out the use of the DOM in the browser— it has graceful degradation and accessibility features that are really important. It's more that there are people with existing Qt or JavaFX or Cocoa dependent projects, or whatever, who are now able to deploy to the web by implementing the UI layers in WASM/WebGPU.
Let’s build a browser inside of virtual assembly code that runs in a browser that runs on an OS that runs on real assembly code (sort of). We could run that on a physical processor, or in a VM (hey, maybe we could run that VM inside a browser that runs on…)