"The older a treatment the more respect it was given. The Greek historian Dordorus, who visited Egypt in the First century BC, wrote that the doctor who followed a text exactly would not be blamed if the patient died, but if he disregarded it and the patient suffered he could even be sentenced to death."source ;Charles Freeman, Egypt, Greece and Rome, Civilizations of the Ancient Mediterranean, second edition, 2004, Oxford University Press, pp. 86.
One of the first things we learn as children is to listen to our parents and other older relatives. This is a good thing for a young child, who cannot yet understand which actions may be safe and which may be dangerous, but in the practice of medicine and science can stifle advancement and new knowledge. This is a problem with the apprenticeship/rote memorization model of veterinary medical education, but is an even greater problem in the promotion and use of many CAM treatments. While traditional medical practices are interesting, and sometimes even manage to hit upon effective treatments, they are invariably bound to pre-scientific notions which often have little relation to the actual causes of disease. The lack of real understanding of most diseases that was common to all cultures until recently led to various philosophical models of health and disease that often involve some type of vitalism-treatments are designed to bring some vital force or energy back into balance. Often this involved using plants, animal parts, or other substances which look like parts of the body or the elements of the vital force which need to be changed, or draining blood or other body fluids to adjust these perceived balances. Some of these treatments were harmful (bleeding, treatments involving heavy metals and other toxic substances, etc), some were harmless but ineffective, and a few were effective just by chance.
As I discussed here, ineffective treatments may be more likely to spread in a population than effective treatments.
Promoters of various forms of traditional alternative treatments often make the claim that the treatments they use are ancient when their relationship to actual ancient practices may be dubious. Another oft-heard claim when traditional practices are criticized is that such criticism is prejudiced and racist. This accusation relates to post-modernist beliefs that there are many, equally valid "ways of knowing". While this approach has some value in the humanities, it does not provide much value when trying to answer a scientific question such as whether a medical treatment is effective or not. Claims of racism or prejudice also minimize the contributions of scientists in varying cultures who may be studying traditional treatments such as herbal remedies for safety and effectiveness, or to discover and develop new compounds that may be useful drugs. Since so many traditional treatments are likely to be minimally effective, ineffective, or even dangerous, it is reasonable to demand strong evidence of effectiveness before adopting them, no matter which culture the remedy comes from. Equal opportunity skepticism is not racism, it is what is required to evaluate any traditional treatment.
Some traditional treatments such as bleeding, or treatments involving "magic" or the manipulation of unmeasurable energies, may be useless at best and actively dangerous at worst. Others, such as the use of Milk Thistle extracts as a liver tonic, have demonstrated some evidence of efficacy for some of it's traditional uses.
The appeal to antiquity is as old as antiquity itself, but should not be used to stifle critical evaluation of ideas.