I see now, I misunderstood your original post. You were saying async/await is necessary because futures work badly, not because all the alternatives (i.e. locks) work badly.

Sorry, my mistake!

Edit to add: futures work badly in every language, so there's no shame in the borrow checker not working with them.

Edit 2: But in that case we're back to "why would Rust want async/await over (potentially green) threads with its first-class support for locks?"