> I'd love to know what I'm missing

afaik, Janet's immutable structs/tuples are flat copies - no structural sharing. Clojure uses HAMTs. So it's truly immutable by default - you'd transform data without intermediate allocations.

In Clojure, the standard library already knows about your data - it has the tools to group, index, validate, serialize, and transform maps/vectors/sets without you reinventing them. In Janet, you have the building blocks but it feels like you're assembling the furniture yourself.

The trade-off is that babashka adds ~200ms to cold start and can be pretty memory hungry, but god, Clojure is so nice to deal with data. For small scripts it may not matter. For processing log files or CSVs with millions of rows, it does.