The discussion around inode zero in POSIX systems highlights the historical and theoretical aspect of filesystem structures. In POSIX, inodes are essential for keeping track of file metadata, but the user-space representation of inodes has evolved, leading some to point out that what is presented at the user level may not reflect the underlying filesystem design or use of inodes. There is an acknowledgment of the complexity of file systems and how they manage inodes internally versus externally, raising questions about uniformity and compatibility in file handling systems.