Good point — especially since as opposed to full continuations, which are essentially impossible to implement efficiently, coroutines / one-shot continuations, have a completely obvious and intuitive implementation: each coroutine is a separate stack and when one coroutine yields to another, it's just a jump to executing code on a different stack.
And with coroutines, it's frequently possible to implement a "multi-shot" continuation, by cloning any mutable parameters, and returning a generator which returns a fresh coroutine each time its called. It's not the same thing as a delimited continuation (is it?) but it's close enough for my purposes.
Normally, you just want functions, but sometimes, you want coroutines. Normally, one-shot coroutines are fine, but sometimes you want multi-shot. I have never once felt like a full-blown continuation was the construct I was missing.
