Almost nobody is doing this, and almost nobody ever will because it breaks accessibility and a whole host of other features. I would save the alarmism for another day.
You're right about the accessibility and other features breaking. You're wrong in saying that (almost) nobody would do this. What (almost) nobody will do is creating an HTML-based rendering engine for windowing (GTK, Qt, wx, etc.) and graphical (SDL, DirectX, OpenGL, etc.) toolkits. It's technically possible, but maintainers have enough work with supporting just the 3 desktop and 2 mobile platforms. In the absence of a proper HTML rendering frontend, there's really nothing you can do other than compile the whole graphical stack and render into a canvas. That's the default for graphical apps under Emscripten - all games and GUI apps currently work that way. The only apps that have a HTML rendering frontend are CLI tools and REPLs, where it's trivial enough to rewrite the rendering in JS. There are frameworks currently being developed that allow rendering of widget trees in HTML or SVG, but they're still immature and not widely used. Well, WASM itself is not widely used, so it's normal.
BTW: were you around in the days of Flash? Because it broke accessibility and a whole host of other features the same way, yet it was still used and hugely popular (there was also ActiveX, which worsened things even more). It began with online games and graphics-rich pages, but it evolved frameworks for generic apps (ie. Flex) and then even CMS engines. Soon enough Flash was used for even blogs and e-commerce. The situation today is different due to the Web having evolved into a more capable and standardized platform, but there's no shortage of devs who would welcome the ability to run their app in the browser, but who dislike HTML/JS so much they would do basically anything just to not have to touch it - accessibility and a lot of other things be damned.
Don't underestimate how irrational people and even whole communities can be.
