I second this, as personally I believe that async is an anti-pattern. It's an unfortunate result of the programming world choosing easy over simple so it could recruit vast armies of inexperienced programmers for profit:
"Simple Made Easy" by Rich Hickey: https://www.youtube.com/watch?v=LKtk3HCgTa8
I'm old school, I want the runtime to do as much work for me as possible so I don't have to. Basically that looks like the runtime providing things like process isolation and concurrency, even if the underlying hardware can't do that. Especially if we're using a high-level scripting language like Javascript anyway. Rust I could maybe see at least providing access to async functionality, but I'd vote specifically against that footgun and go with lightweight threads and message passing (how Go does it) or scatter-gather arrays (there may be a better term for this) with the compiler detecting side effects and auto-parallizing everything else like loops. The simplest way to facilitate that is to use immutable data as much as possible, passed via copy-on-write (the Unix way).
The idea of async being scattered around operating systems and kernels and such is anathema to my psyche. Code smells setting off my spidey sense everywhere I look. To the point where if the world goes that route, I just don't think we'll have determinism anymore. That makes me want to get out of programming.
Note that I feel the same dismay about stuff like the DSP approach used by video cards, where the developer has to manually manage vertex buffers, rather than having the runtime provide a random-access interface. Not being able to make system calls from shaders is also tragic IMHO. We've lost so much conceptual correctness in the name of performance that it breaks my heart. The cost of that is the loss of alternatives like genetic algorithms, which could have provided a much simple roadmap to get to the inflection point we're at with AI, 20+ years ago.
It all just makes me so tired that I feel like some guy yelling at clouds now.