This misconception is also why— for the love of fucking god— people need to stop calling autism a "spectrum". It doesn't matter if it is one, what matters is what people think that means. There is no "extremely autistic" or "a little bit autistic"— those people are referring to cognitive ability. Those kinds of people don't know the difference between autism and general intellectual disability. Autism as we "know" it is a fucking disaster of an understanding, and I will die long before we can get people to think correctly about it.
Also, the problem with people really, super wanting to be "autistic" because it makes them "special", not knowing that autism is a full-neurological phenomenon and not just "you think different". That's another huge reason why nobody actually knows what it is and that, yes, it does in fact have a finite list of symptoms/traits. x_x
Source: autistic, introspective and self-understanding, and rational