As you move beyond simple request-response interactions, the limitations of pure choreography become clear. For any meaningful, long-running business process (like a customer order, a patient onboarding, or a loan application), relying on a chain of asynchronous events between services creates significant problems:

• No End-to-End Visibility: When a process fails, where do you look? In a choreographed system, the overall process state is scattered across multiple services and message logs. Debugging becomes a forensic investigation, trying to piece together what happened and where the process stopped.
• Distributed Business Logic: The logic that defines the process flow becomes fragmented and hidden within each individual service. A simple change to the process, like adding a new step, can require code changes and deployments across multiple services, negating the agility you sought to achieve.
• Complex and Inconsistent Error Handling: How do you handle a timeout or a business error in a distributed transaction? Implementing consistent retry logic, escalations, or compensation (rollbacks) across a dozen independent services is incredibly complex and leads to duplicated, error-prone code.

An orchestration layer centralizes the process flow without centralizing the business logic. It provides a dedicated “conductor” that explicitly models, executes, and monitors the sequence of steps, bringing clarity and control to your distributed system.