This is so misguided that it's hard to even know where to begin. People who develop high blood pressure without a known underlying cause take a pill for it every day for the rest of their life. You could say the same thing, they're not cured, but what actually matters is that they get to live a full life, unconstrained by the disease even if we don't know the underlying cause. Of course it would be better if we were more advanced of a civilization and figured it out, but the important thing is that these people get their lives back.