This is exactly how Flutter (now) works on web - the browser loads a JS/WASM blob, and your app renders everything to a canvas - and you're right, almost everything you mention is problematic.
There is a time and a place for that paradigm, but it's niche. The lack of SEO alone is usually enough to stop it in its tracks.
There is a time and a place for that paradigm, but it's niche. The lack of SEO alone is usually enough to stop it in its tracks.