We Don't Know What Other People are Capable of Achieving
Classifying people limits our expectations of them and the opportunities we give them. Think of a slug. Once you know it's a slug, you know it can't dance. It doesn't do any good to teach a slug to dance either, because they're not capable of it. And even if you say a slug dancing, you wouldn't believe it, because slugs can't dance. But, then again, have you ever seen the sea slug called Spanish Dancer?
People shouldn't be limited by their classifications. All of us have lived with our own limitations our whole lives. We know how to compensate for them. We know what we can do and what we want to do and what hidden talents we have.