ISO 9660 is not at all a general purpose filesystem. Although fairly trivial to reason about and implement, little and big endian systems required entirely separate structures written to disc or files would not be accessible.

Myth 2 was a popular testing media in those days due to Apple and PC endian differences. As I recall Bungie did some clever crafting on the structures to share some of the media between platforms while keeping binaries separated. Even had a fun picture of soulblighter in Finder through icon trickery.

-wrote commercial CD mastering and storage software many many moons ago