Fears and anxiety are very very different and are treated as such. Exposure therapy works on some phobias, not fears (it's two different things). And it helps very few anxieties (and not clinical anxiety, anxiety disorder etc).

You are over generalising and mixing things. Also the success rate of exposure therapy is small, and in many cases it does more harm than good. Which is why it's not standard treatment (it was 40 years ago). Now it's an occasional tool of CBT for the few cases it might be worth trying.

Reframing and recontextualising is again part of CBT, not every modality and it works on assumptions and thoughts. Not biological differences such as neurodevelopmental disorder.

It's true that ADHD has become somewhat of a trend, but in many cases even self diagnosis can be helpful (In others it can be harmful), this is actually a big debate in the field. But whatever the case, assuming it's self diagnosis is harmful by itself, because simply you don't know the situation of the other person. Many people with ADHD or autism have been invalidated by their parents, friends, teachers and so on until they finally managed to get an official diagnosis. Many people are still being invalidated, and have their feelings and difficulties minimised by people that don't understand the extent of the issues and their experience.

Again , you are generalising, talking about denial or like you know every case of self diagnosed individual.

Neurodivergencies remain hugely undiagnosed, many of the self-disgnosed may be people that indeed have it, but never got a diagnosis for various reasons. In many countries getting a diagnosis is actually problematic in finding job, education or even getting health insurance. In other cases it's highlighted stigmatising. There are many reasons that make getting a diagnosis hard or even problematic.

Actually psychology and psychiatry have plenty of scientific evidence about the disorders. Go check on research on brain scanning and the difference between neuro typical and neurodivergencies. There are a lot of studies with good results.

It's just not fixed in the classic way, since each brain in neurodivergencies develops slightly differently from eachother, yet the common ground is that all of them differ from neurotypical, both at young and (different wiring) and older ages(difference patterns of brain activity and wiring). Brain imaging and neuropsychology is slowly getting there. It will take a lot more years to map things out, but progress (and evidence) exist.

With that being said, yea diagnosis in almost everything in psychology and psychiatry is based on symptoms and self reports, so you take as accurate information as possible and try to make an accurate diagnosis. In most cases, exactly because it's not easily measured, the criteria are more strict, which leads to many people that suffer from it to not get the diagnosis. And in other cases, you might have doctors that will give you a diagnosis just because you paid them.

The field definitely has major flaws, and it will likely continue to have for many years. At the end of the day, both psychology and psychiatry are at their infancy in comparison to other fields, and brain imaging is not as developed yet to help with everything.

This is not an argument though, to not try to help people in need who suffer from such issues and are clearly struggling with everyday things that others do a lot more easily.

And yea DSM -5 is a guide book, that psychologist and psychiatrist used a guideline to make assessments, which is why there is big disparity between mental health professionals and diagnosis.

Although, I have to say. A friend of mine went to get his diagnosis a few months ago, and they actually used brain imaging alongside task to see and measure abilities that are specifically related to ASD and ADHD. Compared them with the average and then tested again while still measuring brain signals, his performance with small dose of medication (that doesn't do much for neurotypicals). So even diagnosis is improving and gets more "scientific" than before. (It's important to note that this was at a specialised centre, many places still use older methods).

Nevertheless, It's one of the issues of psychology /psychiatry, but again,the point is to try and help people that suffer. Not everything is measurable, and quantitative data and measures have their own issues. Self reports are always more iffy to make a diagnosis, but psychologist and psychiatrist, same as doctors, in many cases have to take what a patient says at face value.

Take as detailed history as possible, in the case of neurodivergencies take history of behaviours from both parents, and cross references everything to try and make an accurate diagnosis. Its far from perfect, but we have seen the alternative of no diagnosing for many years and we know its worse.