I think the most powerful thing of coroutine is you can switch to other os thread without lost the scope and context as long as you implement the dispatcher of

I think the most powerful thing of coroutine is you can switch to other os thread without lost the scope and context as long as you implement the dispatcher of such os thread (it's likely it will be the os ui thread, because tons of system have such limit). You will usually rely on observer or publish/subscribe model to do such things before coroutine exists. Because you can't magically change the current thread. It's not how it works. And unlike virtual thread. The underlying infrastructure is exposed directly to end user. So you can write your own dispatcher or continuation with ease as long as you know what are you doing. Make it more useful as a low level building block of a high level framework/library.