Yes they are, and it sucks, a lot. But surely there are tons of conditions that YOU are ignorant about. Have you educated yourself about the best way to respond to the whole spectrum of human differences and disabilities? It’s more complicated than “be a good person, don’t be ignorant.” Most people intend to be good people— they just don’t know how. Stuttering is surprising and hard to respond to. Forgive people, smile, don’t shut them out, give them time to get used to it, invite them to keep coming towards you.