I think a standardized bytecode for Javascript could make sense, but designing a VM for JS and then trying to port (say) Ruby or ML to it later would be awkward

I think a standardized bytecode for Javascript could make sense, but designing a VM for JS and then trying to port (say) Ruby or ML to it later would be awkward, and I don't think most web devs are aware of that. Compiling to Javascript is a practical choice now. I'm not a fan of the language, but that avoids a lot of its pain points. I also wonder why these discussions seem to assume we're going to stay with the web stack as-is forever, but that's neither here nor there.