Any usecase forwhich no specialized solution already exists. Source code signatures and Apt/RPM packages are good examples of this.
If you're not using GnuPG, you can pick any format you want! What does OpenPGP add? Everything I can think of is a negative.
If you want an explanation of why GnuPG is dangerous for anything besides email, let me know. But parent post was very specifically NOT about GnuPG- it was about OpenPGP.
What does the OpenPGP format bring to the table, BESIDES HAVING A COMMONLY AVAILABLE IMPLEMENTATION IN GNUPG?