If I'm following your argument correctly, you're suggesting that treating autism as a spectrum is really just lumping together people with actual, severe autism with people who are just more intelligent than average. That's not how it works. Autistic spectrum disorders come with issues with sensory processing[1], planning, actually eating, actually doing anything, social interaction, and a whole bunch more, for pretty much everyone as far as I can tell including the well-paid, successful software developers. The fundamental thing determining where someone is on the spectrum is how able they are to convince people they're "normal", for whatever value of normal is seen as most important. (This is a common enough misconception that some of the more politically active folks even had a hashtag, #SoHighFunctioning, mocking it.)

[1] More specifically, with handling sets of sensory stimuli that society expects everyone to be able to cope with. It's a somewhat open question to what extent "disability", in this case, means "different from what society expects". (Oddly enough, I don't think this even used to be part of the official diagnostic criteria despite being really common.)