It seems like none of the really good language proposals have much traction. Proper Tail Calls have been in the language for TEN YEARS now, but v8 and Spidermonkey still violate the spec and refuse to implement for no good reason.

Record/tuple was killed off despite being the best proposed answer for eliminating hidden class mutation, providing deep O(1) comparisons, and making webworkers/threads/actors worth using because data transfer wouldn't be a bottleneck.

Pattern matching, do expressions, for/while/if/else expressions, binary AST, and others have languished for years without the spec committee seemingly caring that these would have real, tangible upsides for devs and/or users without adding much complexity to the JIT.

I'm convinced that most of the committee is completely divorced from the people who actually use JS day-to-day.