Isn't it ironic that for a language that has new frameworks popping up all the time, the guts of it evolve so slowly?
I primarily work in js and c# so I can't speak for other languages but async/await in c# is incredibly useful and has been around for years. Js feels like it lags a long way behind.
I think it's more or less obvious that languages and platforms ran by a benevolent dictatorship can move much faster than one ran by a committee of several different groups and companies.
This is especially true of JavaScript, where maintaining backwards compatibility is really important [1] -- you have to avoid doing something you can't change later.
They also tend to wait until there's a few implementations of any proposal already. It has to be tested first, before becoming standard.
I primarily work in js and c# so I can't speak for other languages but async/await in c# is incredibly useful and has been around for years. Js feels like it lags a long way behind.