In most cases when working with batched data we also need to be more close to real time. Both the bach and streaming audiences has a threshold when it comes to number of active and live audiences. Rules can in many cases replace the way we use audiences, and with not the some threshold rules. But today we are not able to use event data in this rules. If we f ex in a computed attribute could use event data and not just Attributes we could create rules instead of using streaming segments - that has limitations in the systems.