Within the lifetime of most of us, we have ways of effectively treating infectious disease. Until World War II, until antibiotics were introduced, we did not have methods that cured disease. We had treatments that alleviated the symptoms of disease, but we really didn't cure disease. And that's why it is so important to understand etiology. There are a few other groups of diseases which are now defined by their etiology.
Allergies are an example.
You may go to an allergist because all of these diseases have the same etiology. They have different anatomies, but they have the same etiology. That's the way progress is being made by bringing together diseases with the same etiology. In my opinion, the only way we're going to develop really effective treatments will be to treat the cause of the disease, not the symptoms. We want to get on the train at the very beginning.