I don't think "async-first" is really all it's cracked up to be. It's great for concurrent I/O (webservers). Not great for writing run-of-the-mill sysadmin scripts like rotating log files, doing file backups, etc. Now instead of just knowing that your cron job is doing something one at a time, suddenly you have all these async things happening and you look at your process table and there's 40 node.js processes trying to compress every log file in the system all at once.

And if you don't want it to do that then you have to start managing the concurrency yourself. I've never had to manage concurrency in a shell script beyond just making sure my crons don't run over each other if they take too long.