The brain is not the ultimate general-purpose supercomputer. It was not designed at once, by a genius, on a blank piece of paper. Rather, it is a very peculiar edifice that reflects millions of years of evolutionary history. In many cases, the brain has adopted solutions to particular problems in the distant past that have persisted over time and have been recycled for other uses or have severely constrained the possibilities for further change.
To put this in perspective, imagine that you are an engineer in charge of building the latest and most efficient car. Only after you agree to take the job do you learn that there are two weird stipulations. First, you are given a 1925 Model T. Ford and told that your new car must take the form of adding parts to the existing structure while taking almost nothing of the original design away. Second, most of the new complex control systems you will build, such as the device that rapidly pumps the antilock brakes, must remain on all of the time (not just when the skid is detected). These are some of the types of constraints that have influenced the design of the human brain as it has evolved.
David J. Linden
The Accidental Mind: How Brain Evolution Has Given Us Love, Memory, Dreams and God
Every organ, including the brain, is wired for homeostasis. Homeostasis is the ability of an organism to self-regulate by adjusting its physiological processes. The purpose of this is to maintain internal equilibrium. For example, we have adapted the ability to regulate our body temperature when we get hot by sweating. Sometimes the self-regulating response of the body is not the ideal solution for the problem. For example, inflammation is an attempt by the body to assist healing, however, it can become a problem in of itself as in the case of bursitis and allergies.
In summary, the body has a very powerful mechanism (self-regulation) that assists us with adapting to new situations and challenges. Even though it does not always choose the best solution to rise to the occasion, the brain has an incredible capacity to learn from experience. In this case, neurofeedback provides an experience to the brain of how it can function better. Given a choice, the body will always choose to keep that which helps it maintain better equilibrium or homeostasis.