Just to repeat the point, it’s about intentional versus unintentional usage. Nobody is saying that it’s wrong to test things like familiarity with a wide range of material, only that it’s important to only test the things you intend to test — i.e. what basic scientific principles would tell you to do in any similar situation. That doesn’t mean that you couldn’t e.g. publish a big reading list and say that the English test may include material by these authors since anyone could read that list; it’s just about keeping the competition fair by making sure anyone can learn all of what they should prepare for.