We use Crystal a lot too at Crunchy Bridge. It is used for all of the on-instance programs, the per-region monitoring service, as well as the customer CLI. I'm a big fan of Crystal, and wrote the postgres driver for the language :)
However a main reason we used Ruby was for the production REPL which lets us manage our entire server fleet with like 1/3 of the staff we'd need otherwise.
Amen to that. We reached $2M ARR as 3 engineers at Missive [1]. As the CTO, I can tell life wouldn’t quite be the same without the ability to save the day in the production console at the speed of light.
However a main reason we used Ruby was for the production REPL which lets us manage our entire server fleet with like 1/3 of the staff we'd need otherwise.