The most successful business projects are always those that are driven by an employee who has the authority, vision and influence to drive the required changes in a business. It is highly unlikely that a business owner (decision maker or similar) will realize the changes unless they have one of these people in their employment.
However, the project leadership role typically requires significant experience and skills that are not usually found within a company focused on day-to-day operations. Due to this requirement, with more significant business change projects/programs, outside expertise is often sought from firms who can bring this specific skill set to the company.
~ "Consultant" in Wikipedia