Because you sometimes want to distribute binaries, not entire container images?

Sometimes you can't run Docker (maybe you don't have root permissions to install and start the service). Someone else in the tread said that they're using in their Synology NAS, that don't have access to a package manager.

Docker also will have a much bigger overhead since you basically need to include a whole distro instead of just a few libraries. And I particularly find Docker applications to be sufficient slow to start that I never want to use CLI tools via Docker.