[esprehn]

The web doesn't work without dynamic feature detection. I couldn't find anything in the component model about how this is expected to work.

The DOM is not a static interface, it changes both across browsers based on implemention status and also based on features enabled on a per page load basis.

The multi browser ecosystem also mainly works because of polyfills.

It's not clear how to polyfill random methods on a WIT interface or how to detect at runtime which methods exist.

OTOH the JS bridge layer we use today means you can load JS side polyfills and get wasm that's portable across browsers with no modifications. There's more to the ecosystem than just performance.