Really, it's when you're doing microservices, and each service is deployed to a different container. Typically your business logic is now spread across multiple containers. For example, you might have a recommendation service that looks up location in the geo service. If the geo service returns bad data, then the exception is thrown in the recommendation service. But to debug this properly, you really want to see the logging in both the geo service and the recommendation service, in order. As your topologies get deeper, the problem gets exponentially harder.