While a compiler-free world sounds ideal, my take is there will always be different, newer, syntax developers will want to write that isn't natively supported by the browser. For example, JavaScript language proposals that are maybe in stage 1 instead of the later stages.

Overall, browsers have gotten a lot better at implementing and supporting a common set of web APIs. There's still work to be done, but we're in a far better place than we were five years ago (in my opinion).

100% agree with your sentiment though.