But yeah, for a lot of implementations you don't need streaming. But for pull based apps you design your architecture differently, some things are a lot easier than it is with DB, some things are harder.
(SELECT * from EVENTS where TIMESTAMP > LAST_TS LIMIT 50) for example
Kafka already solves this problem and gives me message durability, near infinite scale out, sharding, delivery guarantees, etc out of the box. I do not care to develop, reshard databases or production-alize this myself.
Not everything needs to be big and complicated.
My main point is, I have zero interest in creating novel solutions to a solved problem. It just artificially increases the complexity of my work and the learning curve for contributors.