I was giving my own personal account of why I wouldn’t want to diagnose myself as I regard myself as mild.
I presume that you're not professionally qualified to 'diagnose' yourself. Most people aren't and even if they are, they can't. The assessment would have to be done by someone else who is qualified.
Self diagnosis is a misleading term. In order to have a diagnosis of anything, you have to have been seen by a person qualified to give that diagnosis. Without that, it's just an assumption, a thought.
You can 'self identify' not diagnose. But self identification doesn't mean it's correct. It's just your opinion. The same as self identification of 'gender'. A thought, a feeling.
Some people who 'diagnose' themselves with cancer can later be diagnosed with Munchausen syndrome (if it's found to be untrue and they are exposed).
I've noticed a lot of 'self identified' people who say they have autism defend their self identification by saying things like 'an assessment for diagnosis is meaningless, it won't help me' blah blah blah. The very nature of my autism meant that I had to have proper answers, I needed to know for definite and when I divulged it to my employer for reasonable adjustments to be made, I had the hard evidence to back up what I said. Self identity is 'shades of grey' and for me it was not enough and went against my personal beliefs.
I don't have a problem with people saying 'I think I may be autistic, I have quite a few traits and I can identify with the struggles autistic people talk about'. However, @WalkthisWayUK I find your comments offensive - 'mild autism' shows a lack of understanding of the condition.
I agree with points made by @RickiTarr. Thank you for your posts.