What make you think they didn’t know? Doctors today know that anti-biotics are useless against colds and other viruses – but if the patient insists, they’ll rx them.
Doctors in earlier times probably had realistic expectations about the efficacy of their treatments. But patients insist they do something – and they pay for those long shot/useless treatments. We still do.
Also, just believing the treatment works will often – the placebo effect is real.
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