We may not be thinking of the same thing, but I have observed at least one reason why medicos "use labels when it is not in any way helpful or even accurate": to administratively justify "treatment".

If a medical professional labels you "X", then
the medico can prescribe you certain drugs,
the medico can employ certain treatments,
the medico can refer you to other medical professionals, and, in general,
the medico justifies their own existence in the medical bureaucracy and, by extension, justifies the medical bureaucracy in the thinking of the people who control budgets.