I think it's difficult for some people to accept because verbal communication is seen as a "given" in our society, so when they experience someone who stutters, they don't understand why you can't just talk normal, like them. Too many people believe that if they can do one thing but another person can't, then that makes the OTHER person the one that is "weird" or different, which is a very selfish view point because all of us have different strengths and weaknesses.