To be clear: you can still easily get this result without anything nearly as complex as promises. But as someone who has written this program many times in many languages, I'm not so sure you're right that this behavior is desirable. People go out of their way to install CLI network tools that don't do this.
I think it's safe to assume that it's a toy problem. A simple example. Picking apart the example is a poor counterargument. It might be difficult to imagine a specific trivial example, but expressing a convincing example concretely can itself be a major diversion. Unless you're saying you can guarantee that your alternative is always better in all conceivable cases?
Similarly, the existence of others wanting different behavior is also a poor counterargument. The fact that someone wants a Bag doesn't mean that someone else is wrong for wanting an Ordered Set.
I agree that it seems a bit pointless unless you're running a huge batch and that I don't think reading from channels in a for loop should be referred to as promises, but I've written CLI tools where running batches of jobs in parallel and printing the results in order is desirable. I don't think it's a generally undesirable thing.
Edit: not quite parallel: I mean with a limited pool of workers, or a partial ordering, or something else that means there's a reason to return results early.
