Disease may be what people have, but illness is what drives them to seek help, even when they may not have a disease as such. In the biological model of disease, this cannot be accommodated. In the systems model, illness is a flag for dysfunctioning at some level.
Many doctors when confronted with illness look for disease.
When this is found the disease is treated but the illness, which may or not be related to the disease, remains untreated. If no disease is found, the doctor often scolds the patient and may even accuse him of malingering or hypochondriasis, both of which are derogatory and morally judgmental terms.