One way to think about it is who does the routing. My understanding of rabbitmq from 10 years ago was that RMQ pushes to connected consumers and to only 1 at a time? You'd need a fanout consumer that does more of the work. And lower throughput overall.

With Kafka it "just" keeps appending to a dumb (but huge) circular buffer. But you can have multiple consumers read off this buffer and can start any point. Downside is customers have to maintain their own offsets (in some storage) but there is now a big decoupling between producer and consumer. This contributes a large part to high throughput too (and consumers can go at their own pace -ofcourse if they are too slow they can fall off the log).