As you said, usually it is enough, but people tend to (over)design and plan for scale, and Kafka does become a better solution above a limit. Shall you touch it, that's another topic. I wouldn't say that it is a rare occasion that you absolutely need Kafka, but a less frequent one, surely. Also I don't think it is a terrible miss to use it if you need a queue with reasonably high demands from it. You'll mostly waste operations efforts and development time. The end result will not differ too much.

Nevertheless, the case from above is a very extreme case of over engineering and premature optimization. To the limit where would qualify it as reckless.