Still, I think talking about Kafka without load feels like Christmas without tree. I thought that was the main point of it. Handling massive loads (by distributing them).
I think that the author just leveraged the existing messaging infrastructure they were already using for other services, and also reused their know-how. Their new microservice will barely register in the overall traffic volume, but they don't need to either deploy dedicated infrastructure or onboard onto yet another technology just to have message listeners.