This can’t be right: if everyone has a disorder, then it’s just an order. It becomes a disorder when it is harmfully abnormal. Yes, normal human thinking is often irrational in regular and predictable ways. The DSM disorders characterize patterns of thought that exceed those normal failure modes in some way. They are explicitly defined in terms of excesses of these thoughts and behaviors.
Take the BPD criteria above:
- Occasionally have fallings-out with friends is normal; BPD is a “pervasive pattern” of that type of instability.
- Not wanting to lose friends is normal; in BPD the sufferer is “frantic” about it.
- An occasional impulsive indulgence is normal; in BPD the impulsivity risks “self-damage”.
- Being angry is normal; “inappropriate, intense anger” that the sufferer can’t control characterizes BPD.
It’s the excess, the extreme, the patterns of thought and behavior that are abnormal in their intensity or frequency, and particularly where these patterns cause problems for the sufferer. Yes, it’s culture-dependent, because ‘normal’ reactions are culturally defined. But being unable to adapt one’s behavior to one’s culture is a practical problem, not a moral one, so it can be cultural and still coherently described as a mental illness or disorder.
It wasn’t added as a separate disorder, but changes to OCD and schizophrenia implicitly recognize that diagnosis, by reclassifying OCD from an anxiety disorder to a distinct group of “obsessive compulsive and related disorders”, removing the requirement of insight (i.e. recognizing delusional obsessions), explicitly mentioning schizophrenia as a differential diagnosis of OCD, and making schizophrenia a spectrum disorder. See this paper from 2016.
The increasing recognition of spectrums and clusters of disorders was a major theme in the change from DSM-IV to DSM-V. That seems like a positive change, and one that goes to your “everyone has everything” theory of mental illness: a spectrum implies that normalcy is on a continuum with disorder.
But again, having a few magical beliefs (lucky coins, superstitions, etc.) is different in diagnostic significance from having pervasive and long-lasting delusions.
I was struck recently by a video of an interview with a schizophrenic man, because some of his delusions remind me of some of yours. For example, at one point he explains that he can’t talk about something because talking about it would make it go away and keeping it around keeps an extra-dimensional being he’s connected to alive.
At another point he talks about how he is god, and god and the devil are the same, how he has to be homeless because he’s the devil, and how his role in the world is to bring magic back from another reality.
I’ve never seen a taxonomy of delusions in schizophrenia, but they probably follow certain patterns, e.g. people from similar cultures having similar delusional beliefs, as they translate similar misfirings through similar cultural narratives and assumptions.