If people are indeed directly accessing a stream, they are violating a fundamental service oriented principle - Teams must communicate with each other through their service interfaces. It is worth understanding this concept with clarity. Assuming we go with Kafka, even if we don't need any additional functionality other than what Kafka provides out of the box, it would still need to be wrapped in a service and treated as an actual service. Otherwise, it becomes a shared resource.
This is one of the core issues that make many ES systems complex. A service owns an event in the same sense that it owns internal state. It's internal to that service and only expose what it finds appropriate, in the way it finds appropriate. That is almost never directly as an event on a public eventbus.
