@midsomermurderess
When I mentioned autism I was not equating it with a personality disorder. I was pointing out how on this site so many users cannot see or hear about bad behaviour, of what ever severity, without immediately reaching for their own diagnosis. NPD seems to be the common go-to now, but see also autism, dementia, ADHD. Not, for the avoidance of doubt, the same as personality disorders...Up to recently, 'toxic' seemed to be the blanket diagnosis. And I doubt that NPD, or narc or whatever, is mentioned so frequently here because posters are encountering it more often than usual. It's remains very rare across the population.
Quite a few posters are insisting that NPD is very rare.
While quite a few have pointed out that narcissists almost by definition are unlikely to seek out a diagnosis-if anything, they are likely to avoid psychiatrists, therapists, etc like the plague! If they DO seek out such people, it is often in regard to other people in their family, family who are not narcs themselves but have been damaged by the narc. In other words, narcs seek out these professionals in order to manipulate them (often successfully, I might add, with the result that the therapist turns against the original clients, the people damaged by the narc!)
I'm aware of the dangers of armchair diagnosis. But when I finally got to read about NPD online in my 30s, that was a Eureka moment: it was as if the author of that particular site (someone herself abused by a narcissistic parent) was describing my own childhood. Her detailed descriptions of the behaviour.
Narcissism isn't just common garden bad behaviour; it is an entrenched pattern of very specific bad behaviour.
I hear those who say the label is just an excuse for the narc to carry on behaving badly. I'm pretty much sure if either of my parents had been given this formal diagnosis, they would constantly have reminded everyone of how it's a terrible illness and how they couldn't possibly be held responsible. So I never shared my understanding of it with my DF (now dead) and I haven't discussed it with my DM either: no point. But being aware of it has given me the insight and strength necessary to stand apart from all the madness.