Earlier quoted context omitted.
For me one of the issue of the current names is that their definition change too much depending on the context and the person interpreting them. For instance if you say someone your arm is 'broken', they understand something is deeply damaged (not just fissured). They might not know the specifics on how it broke, where exactly, how you are healing it or how it impacts you, but they know the basic criticality of it. I…
I think what you're doing is comparing medical vs layman usage. A doctor will tell his patient they have a "broken arm" due to past experiences in speaking with patients using medical terms. e.g, fracture or distal radius fracture in the case of a broken wrist. When it comes to mental disorders, it can be very difficult to accurately classify the severity. It reminds me of how doctors prescribe blood pressure medicat…
Most DSM disorder categories don't perform well on measures of inter-rater reliability. (https://en.wikipedia.org/wiki/Inter-rater_reliability). One implication of this is that the categories can't be assumed to be well-defined scientific entities. Now, the DSM could be a shadow of some more complete, correct taxonomy of mental disfunction—certainly it's based on observation of genuine distress, so it's not completely arbitrary—but by scientific or medical standards, it's very shaky.
Here's an article about the situation in relation to the DSM:
https://www.madinamerica.com/2013/03/the-dsm-5-field-trials-...
It's not uncommon for people who haven't looked seriously at the mental health field to assume that the so-called medical model of mental illness meets the same high standards of intellectual rigour as other areas of medicine, or other endeavours such as engineering. I put it to you that you are in exactly that position: the very basic point you are making ("This is as complex as engineering! Leave it to the experts!) indicates that you are unaware of the unique flakiness of psychiatry. This is contested territory, and many professionals are invested in a certain dubious framing of the situation.