Final answer:
Max Weber is the organizational theorist who advocated for a pyramid-shaped organizational structure within bureaucracies, emphasizing a hierarchy of authority and clear division of labor.
Step-by-step explanation:
The organizational theorist who promoted the pyramid-shaped organization structure as critical to his bureaucracy-based philosophy was Max Weber. Weber's ideal bureaucracy is characterized by a hierarchy of authority, a clear division of labor, explicit rules, and impersonality. This structure is designed to ensure efficiency, provide clarity in roles and responsibilities, and reduce personal bias in decisions.