Not many CEOs are credited with having as much impact as Steve Easterbrook had in his four years leading McDonald’s. During his tenure, the fast food giant nearly doubled its share price, and many analysts say he modernized the company when it was in danger of decline. None of that success could protect his job after he apparently violated a company-wide policy that barred supervisors from having relationships with subordinates. Experts say the company had no choice but to enforce this policy.