The SQS, SNS, and EventBridge services we saw on Days 1-3 all operate at the granularity of a single message. One message is produced → routed → received and processed by a consumer → done. Message retention is 14 days at most, and once a consumer processes a message it either disappears (SQS) or can't be viewed again (SNS/EventBridge, Archive aside). Yet a large portion of the data modern systems generate can't be handled with this model.
Consider this. An e-commerce company generates user click data at 500,000 events per second