a world without dumb people would be a boring world because any one at any given time can be seen as a dumb person; however, if there were no dumb people at all, ever, than we would miss out on alot of fun and entertainment.
Soccer games would not be as exciting either, there would be no kid that runs up and slide tackles a kid only to get stepped on, or keepers that jump the wrong way without even a fake, or shots that go out for throw ins.