Why are many people with aspergers on the internet so pedantic about having a diagnosis?

I'm officially diagnosed with major depressive disorder with anxiety.

I'm very introverted, and don't have a support system or socialize with many people.

I think most people I interact with in person sense that I'm not "normal".

A school counselor talked to me about autism when I was 15.

A psychologist I was seeing for therapy told me that I have Asperger's Syndrome.

Two different women who are the mothers of boys with Asperger's told me they thought I had Asperger's Syndrome.

Two adults with Asperger's told me they thought I had Asperger's.

I've been called weird by dozens of people throughout my life, and have always had trouble socializing with people.

I didn't diagnose myself with Asperger's Syndrome.

Other people have constantly told me that I'm weird, and people familiar with autism have brought up Asperger's without me asking them.

But when I tell this story to autism groups on the internet, they act like I need an official autism diagnosis to get their approval to say I have Asperger's Syndrome.