This all boils down to how we accept something to be "real" or valid. This is an important aspect in science, and especially in the field of medicine.
To get a drug to market, pharmaceutical companies have to show that it works better than a placebo.
I think that is a very important statement, and something that the "alternative medicine" community seems to want to ignore. This is what we call careful, scientific study. If you claim that B causes A, then there must be a clear connection between A and B, and that A can only be caused by B in a controlled manner. In other words, A can not have been caused also by C, or D, etc. In alternative medicine, the effect is VERY small, and small enough that it can't discount not only the placebo effect, but also random chance.