The author mentioned "the Haiku operating system each application is one package, and each package is one file that is loop-mounted into the filesystem to make

The author mentioned "the Haiku operating system each application is one package, and each package is one file that is loop-mounted into the filesystem to make its contents accessible." Now if you don't ever need to interact with application files why invent all this complexity when you can just expose the files individually and not ever care about that again.