Linux distros are shipped as binaries yet you can still build them from source, and are certainly not controlled by one company, I don't see why that would be the case here.
Would you require every website to come with architecture-independent source code? What happens if it doesn't match the compiled binary? Or would the browser compile it every time?
Would you require every website to come with architecture-independent source code? What happens if it doesn't match the compiled binary? Or would the browser compile it every time?