What different way of doing things?

If I want sequential execution, I just call functions like in the synchronous case and append .await. If I want parallel and/or concurrent execution, I spawn futures instead of threads and .await them. If I want to use locks across await points, I use async locks, anything else?

> 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