The different philosophies of "explicitly annotate async functions" vs "implicit async" vs "create os threads with polling" etc will always continue because they all have tradeoffs.

So, the "simplification" or a "unification" of a concurrency model always comes at a cost that some programmers don't want to pay. Whenever you see, "Language <X> has solved the color problem so it's not an issue." -- the reflexive skepticism should be, "At what price, and do I want to pay it?"

I think it's instructive that Rust had a clean-sheet start to design a new language and so far, they've rejected Go style "channels" as Rust core syntax and instead, adopted the async/await paradigm. You don't have to program in Rust to get the gist of the following previous comments about their thought process:

https://news.ycombinator.com/item?id=21475154

https://lobste.rs/s/bfsxsl/ocaml_4_03_will_if_all_goes_well_...

https://lobste.rs/s/y3fsrm/what_is_zig_s_colorblind_async_aw...