I do wonder why this use case - using wasm as cross-platform, cross-architecture portable binaries with performance profile "close enough" to optimized native code - is not more common. One can easily imagine an OS directly supporting such binaries even, JIT-compiling and caching them as needed.

Reminds me of the commercial of the old auntie using her wall for offline Facebook with her friend pointing and confusedly declaring "That's not how any of this works!"

That's one way to write software that can seamlessly adapt to any future architecture changes. And Windows on ARM is already a thing.