You cannot just spray a plant with a pesticide, or release a bottle of predatory mites and expect your problems to be solved. Pest management requires an organized thought process that has to be considered before you have a pest problem. This is the foundation of IPM (Integrated Pest Management) and biological control is just on tool used in IPM.
IPM is the practice of preventing and suppression of pests. Several tools are commonly used, including scouting, resistant varieties of plants, and cultural practices. Pesticides are only used when softer approaches have not worked. When pesticides are used, they are carefully selected and used in an environmentally responsible way.