Yes performance is partly bio-chemical, but what do you think that human body is lacking bio-chemically? What imbalance are you expecting? Aren't you refering to medical practice rather than 'doping'? Unlike J.R. I believe to some degree in medical practice. Why wouldn't I? If I had a tropical disease and the doctor told me I will die if I dont' take drug X, do you think I would doubt him?
A healthy body is not lacking anything bio-chemically. To suggest otherwise as the 'PED' dogma implies, is a continuation of the drug folklore, the mythology of the ages, the belief in magic potions, shamanism. Why tis witchcraft. Seriously, it is the same mentality in modern guise. A human frailty to which almost everyone is, was and forever more shall be enslaved. Isn't that why alchohol, tobacco, cocaine, ampetamines, heroin etc are all uncontrollable in society? Well the same human frailty is not just a problem for addicts is it? It's a perception to which we are all vulnerable, that things would be better with some exogenous chemical assistance.
Back to the bio-mechanical efficiency point; it determines your performance level. To run faster, or bike faster you have to output more power overall than you did before and that is controlled neurally.
Now you have read Daniels' research haven't you? Remember that graph with the oxygen uptake for marathon runners? It showed that the difference in percentage VO2 max for 2 hours or 3 hours was miniscule. Do some simple arithemtic, elite runners use less oxygen in a race, nor more. Less energy. This is the opposite of the 'Bigger Engine' concept that almost everyone believes. Therein lies the problem. It's conceptual. A wrong philosophy is prevalent.