We know so much more about how to create programming languages today than we did then, and the whole "Year of the Linux Desktop" has become a WebAssembly meme now every year since its introduction six years ago, with it getting popular always next year, next version, with feature XYZ. Seemingly creating unmaintainable/debuggable mess from external languages with no true 1:1 into WebAssembly isn't as big of a hit as the originators expected.
Yet every time someone asks why there hasn't been movement here it is "Year of WebAssembly is next year!!!" WebAssembly has managed to slow actual progression towards something good. With the browser monoculture you'd think it would be easier now than ever to start a fully integrated second language with WebAssembly compilation for backwards compatibility.