[dnanian]

Because we cannot authorize against a network drive sufficiently to ensure proper metadata preservation, etc. In addition, a network volume is a 'virtualized' file system, where it might 'act' like HFS+, but it's actually NTFS, EXT3, FAT32, etc.

Supporting all those specialized and not-at-all-the-same disk formats (and all the potential problems in the network transport layers) wasn't something I wanted to do.

That's also why Time Machine uses an image when backing up to a network volume, by the way: the image acts like a local drive, and a real file system, which puts everything on the same level...