I think this is largely a rephrasing of one of the findings of dealing with NoSQL vs. Relational DBs, which is that for a subset of problems relational DBs have been used to solve in the past, NoSQLs are perfectly capable of replacing them, but not every problem a relational DB handles can be handled by a NoSQL without investing significant time and effort layering more complex systems on top, at which point you've basically implemented a poorly optimized ad-hoc relational DB. In this case, Redis, with the new stream type is capable of handling a subset of problems that have previously required Kafka to solve, but it isn't itself a replacement for Kafka in all situations since there are several important features of Kafka that aren't available in Redis.