Why did Helmuth von Moltke believe rigid operation orders would not work for large armies?

Helmuth von Moltke (the elder) recognized that the traditional method of maintaining tight control over subordinates through short, explicit orders was impractical for modern warfare. With the advent of railways, armies could be deployed on a massive scale across battlefronts extending for hundreds of miles, rather than the small battlefields of the past.1

Moltke understood that in an army of millions operating over such vast distances, a commander could no longer exercise the direct, rigid oversight required by traditional "operation orders." To address this, he instituted a system of "general directives." Under this approach, subordinates were assigned long-term tasks in general terms but were granted considerable latitude to use their own initiative and discretion in executing them. This shift in command technique was essential for managing the complexities of large-scale, modern military operations.1