> I've said before and I'll say again: this kind of async is a design flaw. It's a retrograde step that brings all the cognitive overload of cooperative multitasking back.

You seem to be assuming that preemption is always needed or wanted. This is not always the case. The lack of preemption actually simplifies a number of factors that simply aren't relevant in async scenarios in a single program.

async/await patterns are actually the perfect solution for capturing the minimal context necessary for resumption after the async operation completes.