You know who is going to latch onto that? Every goddamn teenager in the world (and many adults). Now, if you dig deeper, you'll see that Asperger's is a lot more complicated than a list of vague symptoms and needs to be diagnosed by an actual clinician, but the beauty (or horror) of Web research these days means that anyone who feels like "I've always known there was something different about me" can google up a list of symptoms or an Internet quiz, and diagnose themselves, despite the caveats on those sites.
Just so we don't slander the people with real Asperger's (you know, the ones that have actually been diagnosed), let's call the fake ones Ass Burgers. If you do this out loud, no one will even notice.
For visualization purposes.
There's a few common reasons that Ass Burgers self-diagnose.
1) It's not your fault anymore!
If it's a real disease that real psychiatrists have a name for, and real patients get treated for, then no one can blame you! No one can call you a rude asshole for talking about your Transformers collection for two hours straight during someone else's farewell party. You have a condition!
2) You're special!
Some people with Asperger's can be very intelligent. They might not count cards, but they can be very focused and knowledgeable about specific subjects, and think in unconventional, creative ways. An Ass Burger would love to be able to hitch their wagon of bad social skills to neat traits like these.