user doesn't want to download an app, since that has a lot of friction. Going to a url and waiting (even if the download time is the same) feels like there's less friction, and so this idea of shipping a blackbox is more desirable.

The only problem really is the jankiness of any non-browser controls. The user expects a good right-click context menu, keyboard navigation, scrolling, etc, which all would have to be implemented if you're compiling a native app into WASM. But if the app itself is just HTML+javascript, then shipping a WASM browser, then using that browser as the app layer solves all of those UX jankiness (since the user should not really be able to tell it's a WASM browser).

The idea is insidiouly bad for user freedom, but great for businesses like google (who wants to control the user space completely).