As an herbalist, I believe strongly in the power of the entire plant, the entire organism. Are there times when the extract of one constituent of one plant is preferable? Surely, I can't say that there aren't. However, nothing, when possible, can compete with the whole food, the whole being of one herb.
Those constituents which might be irritating, caustic, or too strong are tempered by the ingeniousness of natural order--mucilage to counter alkaloids and tannins, relaxants to counter stimulants, nutritives to rebuild, astringents to re-tone. Food is indeed our medicine and, likewise, our medicine--as often as possible--should be food.
But like so many called to the healing arts, the body of the healer (I'm using that term incredibly loosely) is too often neglected and, at least in my case, the brain is too full of possible remedies to create a simple solution. Too often we complicate our own situation--the price of sticky subjectivity.