The danger of naming mental disorders (or any other abstract concept) is when you confuse the map for the territory.
The map (the name) should serve as the best possible mental model of the territory (the actual, descriptive physiological condition) - not as the thing-in-itself.
It is tempting to stare at the map when the territory is obscured by the fog of war. The rigor of the SCID very much hides the fact that several places on the territory have similar features but are miles apart. And then every observer loves certain places and hates working in others.
As bad as the state of diagnosis is (some say >50% for certain conditions) there is no way around a diagnosis for treatment as one needs to make decisions and these need to be based in whatever tenuous grasp one has on reality. At this point imho. we can only try to make sure all sources of bias, tendency to defend previous decisions, treatment capacity and financial considerations (diagnosis is key to insurance payments) are as far isolated from decision making as possible. There is lots to be done. SCID is only the symptom.
The name of a disorder mental or physical is a map or model in the same way that the name of a town or street is. Which is to say, it's not, though it's necessary for identification of a component of a model.
“Diabetes mellitus” isn’t any kind of a model. It's a symptom description dressed up in Latin. We've since attached a useful model to it, but the name long predates the model and has little to do with it.
I am of the opinion the worst part about naming disorders is the holy hell some groups will have if what they suffer from is described as a mental disorder. Then you will get the other side of the coin where people self diagnose and that sets off a different chain of issues.
So it become six of one and a half dozen of another. For the benefit of the medical community yes we should name them or slot them into broad categories. For the public its best to probably just use broad categories
The map (the name) should serve as the best possible mental model of the territory (the actual, descriptive physiological condition) - not as the thing-in-itself.