That's my understanding, and why you need full continuations to handle all effects. In my mental model a coroutine gives you an execution point that you can res

That's my understanding, and why you need full continuations to handle all effects. In my mental model a coroutine gives you an execution point that you can resume, but you are not allowed to resume execution points you have previously resumed. You cannot, for example, implement backtracking search with just coroutines as you need to to return to previous execution points. (Look, you can implement anything with anything. Turing completeness etc. This is about implementing it in a natural way using the effect handlers.)