Cloud services do go down and it's out of your control when they do. If something must work, you need redundancy. Kafka is often used for financial application

Cloud services do go down and it's out of your control when they do. If something must work, you need redundancy. Kafka is often used for financial applications that must not miss events, so having a backup buffer is a reasonable strategy for those use cases. Things like tracking data is likely not worth backing up due to high data volume and low external visibility when data is dropped.