Yes, interrupt is better, and the article explains how to do that a few paragraphs later:

        for n := range in {
            select {
            case out <- n * n:
            case <-done:
                return
            }
        }

If you allow pipeline stages to interrupt their receive loop instead of draining the inbound channel, then _all_ send operations need to be governed by done. Otherwise the interrupted receive loop may block the upstream sender.

The loop (particularly `range c`) keeps getting element out of `c` and assigning it to `n`. If it's "done", then `n` wouldn't be sent into `out`, but still gets read from the channel `c` constantly. In other words, it's the loop itself that makes sure everything sent into channel `c` is consumed.

If `break` is used, for loop is terminated once it's "done", hence nothing would be reading from channel `c`. The previous station in the pipeline would then block at sending operation.

I think its so that the channel is empty, and will have no references so it will be garbage collected.