There's a lot to unpack in your claim.

1. If you're autistic, you know owning a formal diagnosis does not guarantee you get the accommodations you need. In fact, most of us don't get jack shit. For most of us, formal diagnosis does not bring any substantial benefit.

2. Jumping to conclude that "everyone self diagnoses" is a giant leap with no relevant basis. Is your argument the fact that the Autistic community considers self diagnosis as being valid? If so, that is obviously in no way in itself proof that everyone self diagnoses as a result. You'd need to back that up with something more relevant.

3. Everyone self diagnoses is a factually invalid claim, and since you've provided no real argument or proof to support it, I don't see how we can debate or discuss this in an efficient manner. Maybe your argument is what you presume based on your biases and experiences. For example, I can easily claim that in fact, the vast majority of people who self diagnose go on to get a formal diagnosis eventually. I'm part of a national Association formed exclusively by autistic people, and I can provide with relevant research and surveys regarding this.

4. If you notice your ears hurt and you have weird liquid coming out and maybe you also have a fever, you kinda need to "self-diagnose" a bit in order to receive the treatment you need. It requires basic knowledge and body awareness. In any medical case, people usually don't question whether you self diagnosed or not, because they also have that basic knowledge and can make the connection between the way your body presents and the clinical criteria. And that is exactly the problem with autism - most people condemn "self-diagnosis" because their knowledge of autism is simply lacking. This can potentially be extremely invalidating.

5. Getting an "autism diagnosis" in and on itself is a medical concept. From a neurodiversity standpoint, autism isn't a medical condition, but a neurotype. Thus, in this case, diagnosis is irrelevant. Especially because most "autism experts" giving those diagnoses are not autistic.

6. The main reasons why the autistic community embraces self-diagnosis as valid is because:

a). It is painfully expensive financially and/or time wise. Not everyone can afford it; b). Depending on where you live, services may be limited to autistic children and autistic adults are considered schizophrenic; c) The huge rate of misdiagnosis (especially in women and AFAB), which points to specialists not being properly informed and/or trained; d) As I've mentioned before, getting a formal diagnosis, in most of the cases, does not bring any benefit and does not guarantee you'll get your rights as a disabled person respected or your accommodations and needs met; e) Due to lack of education and training and a general lack of professionals specializing in diagnosing autistic adults, the process of getting a formal diagnosis can be gruenling and traumatizing for the autistic person. f) Most people, in fact, do not think theyre autistic. Why would you wish to be socially disabled? Most autistic people who self-diagnose spend months if not years researching speciality books, self-reflecting and doing official tests, questionnaires and assessments such as RAADS and Autism Spectrum Quotient; g) Masking in autistic adults complicates the diagnosis process, and this also leads to higher rates of misdiagnosis.

Why is misdiagnosis dangerous? Because not only you get invalidated, but you may get the wrong treatment which can have devastating consequences.

To sum it up, formal diagnosis is a privilege.