The DSM has many flaws, notably being a categorical tautological discretization of some stateful, high-dimensional networked process.

But one thing they do get right is the constancy of causes in the different families of personality disorders. NPD, for example, is not an 'evolving personality', it's only classified as NPD if it's rigid, generally unchanging, and pervasive by its very nature.

Misunderstanding some group of people then claiming action like 'throwing the shrinks in jail' based on that misunderstanding is quite frustrating to me. In addition, the DSM was never meant to be an official manual, just a lingua franca, at least in the early days. You can blame the prevalence of needing discrete billing codes and the stubbornness of the APA to change in more difficult parts of it for its prevalence today.

Please understand the difference between temporary self-absorption and clinically significant chronic self-displacement into secondary, superficial images of self. The first one is growth and struggle, the second is a supremely painful disorder (arguably all of the lack-of-self-love/Cluster B/reactive disorders are, I'd contend).

Right with you on destigmatizing. But that being said, people with narcissistic traits are generally not safe at all, in the least, to be around with any kind of emotional proximity, to be honest as I can with my personal experiences in and around the world. Not that you, or I, or anyone else should stigmatize or hurt anyone on the NPD spectrum 'just because', but I feel very strong that it's basically impossible for anyone on that spectrum to not involve you past a certain point due to the deep desire and need for others for self to feel safe -- that's where I'd argue with the crossover of BPD is with narcissism, although hyperempathetic as opposed to low to literally no empathy at all.

Just my 2 cents, hope this helps clear things up a bit.