"If we manage to self-treat ourselves into passable normality, few people believe we ever had a serious problem in the first place!"

Elaborating, I think, rather than disagreeing: Self-treating into passable normalcy is basically life. One of the characteristics you have to have in order to be diagnosed with any psychological disorder is that it has to be interfering with your life. Absolutely everybody can read the DSM and find a good half-a-dozen things they may have tendencies towards, but if it's not interfering with your life, it's not a disease/diagnosis. Liking a clean space does not mean you're on the "OSD spectrum", being a bit nervous around spiders does not mean you're on the "phobia spectrum", etc.

"Healthy" isn't a single point in psych space, if for no other reason then that there isn't a "perfectly healthy" person available to define that point for us! It also certainly isn't a well-delineated boundary, but it is clearly not a single point, and even within the space of "healthy" there is clearly a lot of diversity.