This is an argument people have heard time and time again. When a lot of people hear the word "autistic," the many stereotypes that have been fed to them by society come to mind. They think of Rain Main. They think we are all savants. They have an image in their mind that in many cases, couldn't be further from the truth.
The fact of the matter is, autism is a spectrum. It may manifest itself in that one may need assistance in many areas of their life. It may present itself in that one may appear typical to the outside observer. Then you have everything in between.
The think to remember is, just because someone doesn't appear to fit those skewed stereotypes doesn't necessarily mean they can't be on the spectrum. Yes, some people may be balancing on the line between on the spectrum and off, but nevertheless, they may still be living on it. Never downplay their struggles OR strengths, just because you can't see them on the outside. Oftentimes, these are things you may not have any idea about until you get to know a person!