Yup. I know autistic people who live in group homes or assisted living facilities and use the Internet. It happens all the time, thanks to the way that autistic people can be really good at one thing and really suck at something else simultaneously. So, if you happen to be good at typing out your thoughts, but suck at talking, or at taking care of yourself... well, then you're likely enough to show up on the Internet and have people say, "But you can't be autistic! Autistic people don't use the Internet!"

Autism is a life-long disorder. While you can "lose your diagnosis" (if this happens, it usually happens when you're a child) because you no longer have significant impairment from your autistic traits, your brain will always be wired that way; you will always have the autistic cognitive style and neurological arrangement. Autistic children grow into autistic adults; and most of the time, those adults can still be diagnosed with autism.

Because autism has only been well-known for the past decade or so, it is not uncommon for people with either milder autism, or autism that masqueraded as something else, to have grown up without a diagnosis. It does take some doing to figure out the diagnosis in an adult because of the confounding factors: Parents may not be available; childhood memories may be clouded; many compensatory skills have been learned and implemented; a great deal of effort may have been spent on erecting a "normal" facade. In the case of people who have had some other diagnosis, whether correct or incorrect, there is also the problem of figuring out the true nature of traits that have always been described in terms of that other diagnosis. In many cases, it takes a specialist.