I got that! The problem was more that I was thinking as if the world could be divided up into sealable boxes. In practice, we can do a lot focusing on one area with 'no effect' on anything else. But this is because the sorts of actions we do are limited, we can't detect the low-level impact on things outside those boxes and we have certain unspoken understandings about what sort of thing might constitute an unacceptable effect elsewhere (if I only care about looking at pictures of LOLcats, I might be 'neutral to the rest of the internet' except for taking a little bandwidth. A superpowerful AI might realise that it would slightly increase the upload speed and thus maximise the utility function if vast swathes of other internet users were dead).