It's what you know, what you are willing/able to learn and how hard you're willing/able to work that matters (together with a certain degree of "luck" as well).
In turn, what causes people to be willing/able to learn and work on certain things? Our preferences and aptitudes are primarily stored in our neurological makeup. So neurological differences (whether inborn or acquired) will cause people to behave/emote differently.
Of course, there will be lots of people with Asperger's who love interacting with others and enjoy great interpersonal success, but that's the point of a pre-disposition -- it refers to a correlation, not a hard-and-fast rule.
I don't have statistics for people in the autism spectrum, but I would not be surprised if they trended heavily toward professions that focused on intellectual work over interpersonal interaction.
So, I'm just saying, it is a disability, and I expect adults w/ AS also trend to underachievement. Anybody know a brilliant but difficult person (or two) delivering pizzas or working as a museum guard or the like? I do.
FWIW, my 5 y.o. has AS, so I've thought about this quite a bit.
There's a lot of stigma of "oh, I could be programmer too if I was willing to be a nerd".