What about screen readers and mobile users? There's all these useful accessibility tools that would also have to be reinvented for canvas based apps.
Text selection and getting it to bring up a keyboard is iffy on the canvas-based things you linked to (I'm looking at them on Firefox for Android on a Pixel 6). Sure, the VB one is a desktop app. But the original (non canvas) version of that app likely worked with windows screen readers, and that is lost in this reincarnation onto the web. Good old fashioned DOM already has pretty good native accessibility support for mobile phone UI.
There's a lot of things that have been thought about when it comes to usability and accessibility, in both the web, and traditional desktop/mobile UI frameworks.
Reimplementing those UI frameworks in canvas in a browser environment requires mapping the a11y bits too, not just keyboard+mouse input and rendering to screen.
Not to mention Qt and Gtk and the older Android framework apps all use forms of markup and styling which are inspired by XHTML and CSS and document object models......
