The traits of ASD / ADHD have always been there in humans. We just never had a clinical diagnosis for it.
The lack of diagnosis been a blessing and a curse. On the plus side, having a diagnosis can help family understand why a person acts the way they do (eg hypersensitivity, lack of empathy, zero tact etc) and manage and support their way through life.
On the negative side is the societal baggage that goes with it.