Things change. Just because it was originally made for documents doesn’t mean that it hasn’t undergone such huge changes that it can literally drive FPS games at 60fps without a sweat. And I say that as someone who really doesn’t like many of the underlying abstractions, imo CSS+HTML are just thoroughly badly designed, none of them would be whole without the other resulting in extreme close coupling (layouting for example cannot be done without the other).

Also, should I really download a random exe to order a pizza? Plus, especially because the protocol is stateless a web app makes so much more sense (then replicating the state at the backend side).