I so strongly agree with this and it's not just based on my own experience, but many people I know.
Growing up broke and in sketchy places with sketchy people will induce plenty of anxiety. Then I managed to get out of all that as an adult and starting a career.
The anxiety never fully went away, but it now presents itself the way one would expect instead of "weirdness". Maturing and having a more stable life happened to my friends also and nobody says "I think I'm autistic" anymore like we did in high school and college. Now it's hard to distinguish if we were saying that to ourselves as a slur in self-deprecation, or if we really believed it. Young people are just awkward and too many people get older without letting go of the things they told themselves a long time ago.
Make of that what you will. I know my story is super common, but the only reason I bothered to write this is that it doesn't get said enough.
Spend a moderate amount of time with some humans-- e.g., war veterans-- and you'll find that denial of a diagnosis is common enough to trivially disprove this statement.