Isn't that the whole point? We are teaching children badly by always giving them clear-cut problems that always have an answer, when the world is full of fuzzy problems that may not have an answer.

Given the environment, why wouldn't the children guess? For years, we give them homework and tests where a guess is always equal to or better than no answer at all. But that's nearly the opposite of how the world works, so we're clearly teaching them the wrong things. I don't see how revealing that is not "fair".