> It forces programmers to learn completely different ways of doing things, makes the code harder to understand and reason about, purely in order to get better performance.

Technically, promises/futures already did that in all of the mentioned languages. Async/await helped make it more user friendly, but the complexity was already there long before async/await arrived

Yes - I was really talking about "asynchronous programming" in general, not the async/await ways to do it in particular.