But this is worse because the interrupter may be doing it in good faith, as in, "I already predicted the rest of your paragraph, let's save 50 seconds of our lives."
edit: unless they're a "serial interrupter" as in sibling comment, we have one of those
The problem with this is that when they fail to predict you usually end up having to repeat the whole argument, to explain it to them the subtle difference between what you where trying to say and what they thought you where trying to say. Usually wasting more time and infuriating you.
It's better to identify those kinds of mispredictions and correct them as early as possible, otherwise the communication barrier will grow until everyone gets infuriated anyway.
edit: unless they're a "serial interrupter" as in sibling comment, we have one of those