What bash is unavoidable? The aliases and functions you define in your personal shell, sure. But what else?
* Installing or starting your general-purpose runtime, passing the right configuration options
* Project glue where introducing general purpose language makes things more complicated because of tooling or startup.
* Simple cloud-init scripts
* A command line tool is simply the best library for the job and you don't want to get a general purpose language just to immediately shell out.