1. At least some autists most certainly could function, even when that old man was a kid. It's just that people understood the condition less back then, thus the stereotypes. Also, due to this lack of understanding, many people who had Autism or another spectrum disorder but were functional went undiagnosed.
2. ASD is most certainly not made up, and if you actually took the time to do the effing research you'd understand that.
3. ASD is not a disease, it's a disorder. Disease means that the person suffers from many negative effects with little to no positive trade-offs. Disorder means that the person is simply abnormal in a very noticeable and/or significant way. Learn the difference.
Please do the research before making sweeping judgments about people and conditions. The people who identify/discover (not sure which word is better) these disorders are much more qualified to study psychological conditions than you are.