I like this technique because of the "mystery" element to it. The example McCloud uses to illustrate closure is the image of a man crying for mercy while about to be chopped to death by an axe. Do we see the sad bloke get chopped to pieces? No, for instead we have a panel focusing on a city and a high pitched scream. The scene to depict closure is tense because of not what it shows but what it might show. Could a limb have been lopped off? What are the details of the violence? That is up to the reader to decide. As McCloud says above, the man with the axe is not the murderer. The reader is responsible for the killing because the reader's imagination made it that the man cried bloody murder (literally) at the hands of a psychopath.
With television and movies, imagery and action is produced to us piece by piece. We don't have to think how things might happen from time to time. But with comics, that's a different story. A reader would read panel by panel. Regardless if it is moment to moment or subject to subject as Japanese comics like to adapt, a scene may surprise the reader further because the reader is responsible for interpreting the action.
This is what makes comics quite fun to read because not everything is spoon fed to us. Reading comics is like reading conventional literature, provided if is written well enough. Readers can interpret a scene of Rorschach of Watchmen fame (or infamy) coming out with an axe and aiming his attention towards two hapless dogs. We see Rorschach raise the axe in one scene, but do we see the finished result on the next panel? Not at all, for we see a ink blot test resembling a slain dog's head. That's the beauty of closure. The action is not presented to you on a platter. The reader is the one either customizing food on the platter or making his or her mind with how the food on a platter appears.