Do you really see people claiming to be aspies who aren't? I don't understand why someone would do that.
Anytime people diagnose themselves with something there are going to be many who are wrong. People are starting to hear about AS now and people who have had a hard time in life and don't have good social skills or aren't liked, etc could naturally try and find a reason for it. Having AS could explain their troubles and why they don't have friends. When someone has had troubles like that in life they naturally want it to be because of some reason that they can't do anything about. It's a lot easier to accept "I never had friends and barely any relationships and people don't like me because of how AS makes me act and come across to others" rather than "Nobody really likes me because I'm a self centered jerk". I'm NOT saying that AS makes you act like a self centered jerk, I'm simply using an example.
Also, people with personality disorders may know that something is wrong with them but not know what is wrong with them so because the internet has everything you ever wanted to know about anything, and because there are tests to diagnose you with anything out there, they could easily take the AS test and get a score that says they probably have it. Hypochondriacs could easily do that as well. I know that when I had my panic disorder and agoraphobia I was a terrible hypochondriac. I was convinced that I had anything and everything that crossed my mind and was constantly researching things. I'm so glad we didn't have internet back then!
The trouble with online tests is that they are subjective. While subjective answers are important on some topics like what you think and feel, there are many things that you can't answer about yourself objectively. You need a professional to diagnose you with the AS not only because it can mimic many other things, but also because it's pretty complicated to diagnose.
Just being nerdy and not having social skills and having extreme likes and dislikes of things and feeling overwhelmed by stress or sensory things are not the only issues with AS. There are lots of other things that the online tests don't cover.
I don't think it's very important to get a diagnosis especially after middle age unless you need it to get disability or you have severe issues that a diagnosis could help in getting accommodations or therapy for. It's important for kids to be diagnosed so that they can get the therapy they need to learn to adjust to the world and fit in, and so that their parents can adjust things at home for them so they are more comfortable but it's also important for the parents not to go overboard with it to the point where the kid is not at all prepared for the real world.
I think my youngest son has a touch of AS. I've seen a lot of symptoms with him. I told him about it and asked if he wanted to go see someone about it but he's not interested in it. He doesn't have social problems but he has quite a few other issues that are AS issues which made me suspect it in him. He may not have it at all, but the intensity of the issues he has makes me think he does. He told me that he's doing just fine and if he ever has problems that he needs treatment for from it then he would see somebody but until then he's not interested. He's hardcore about taking life as it comes and learning to deal with it the best he can. He was born completely deaf in one ear and didn't talk until he was four years old. We were terrified back then because we thought he had something wrong with him. He was doing fine developmentally otherwise but he just didn't talk. They couldn't really test his hearing very well at that point in time but they could tell he had some issues with that ear. It was only later on that we found out he was completely deaf on that side. When he was little they said he could get an implant when he was older but he said he didn't want one. We thought he would change his mind when he was old enough to get it but he never wanted it. If he's that serious about not trying to get anything done about a problem as important as being completely deaf in one ear, then he's not really ever going to care about whether or not he has AS. However, I never told his teachers or anyone that I suspected he has AS because he wasn't diagnosed with it and the problems that the AS caused for him were things he was going to have to learn to deal with in life anyway. It took a lot of time and work but he's finally learned to deal with those things, which is good because he's got a job now and if he hadn't learned to deal with those things he couldn't have kept it this long and be doing as good as he is at it.
So, in some instances it's good to have a diagnosis and in others it's not really needed.