Why can't files be manipulated by inode?

Question

Why is it that you cannot access a file when you only know its inode, without searching for a file that links to that inode? A hard link to the file contains nothing but a n

Answer 1

Some Operating Systems do have that facility. For example, OS X needs it to support the Carbon File Manager, and on Linux you can use debugfs. Of course, you can do it on any UNIX from the command-line via find -inum, but the real reason you can't access files by inode is that it isn't particularly useful. It does kindof circumvent file permissions, because if there's a file you can read in a folder you can't read or execute, then opening the inode lets you discover it.

The reason it isn't very useful is that you need to find an inode number via a *stat() call, at which point you already have the filename (or an open fd)...or you need to guess the inum.