reading the stuff people have written here I could easily believe I am autistic , I can see nothing in the descriptions that doesn't fit. But I am not as far as I know.
So? Go and read about second-year syndrome/medical students' disease. https://en.m.wikipedia.org/wiki/Medical_students%27_disease
It's totally normal to read about a condition, hear people describe what it's like, and notice where it fits you. We're pattern-matching animals with a strong tendency towards confirmation bias.
Maybe you're autistic and maybe you're not, but the fact that when reading descriptions of autistic traits you react like any old ordinary human being (whether autistic if not), with normal pattern-matching, confirmation bias and a bit of healthy paranoia, is neither here nor there.
Or go and read about the Barnum effect. https://en.m.wikipedia.org/wiki/Barnum_effect
The way that autism is written about online, the descriptions tend to be written in such a way that, if taken in their broadest sense and by the average layperson, they could apply to everyone, but can feel very personal and specific to the person reading.
For example, social difficulties. Almost everyone feels socially awkward sometimes, or feels tired out after having to present their best face in a crowded environment for many hours. But most people don't let on about the fact they feel like this. So a normal person can read a description of autism that mentions social awkwardness and social exhaustion and think "OMG IT ME".
This is why you need experienced clinicians to assess people to determine whether they meet criteria for an ASD diagnosis. The criteria were never intended to be applied by laypersons with no experience of training, to themselves, and if you do that, you get the same phenomenon that happens to medical students where they notice that they have all the symptoms of a brain tumor/multiple sclerosis/something exotic and rare that they just read about.
You can't dismiss other people's professional, clinical ASD diagnoses as some kind of pathologisation of harmless quirkiness, based on your own spurious musings resulting from an inadequate understanding of medical diagnosis and cognitive biases. (Similarly, I'm sceptical of any self-diagnoses of ASD, too.)