[m463]

Target disk mode + firewire was wonderful.

If your machine was screwed up, you could plug another machine into it in target disk mode and boot off that (external) "drive" and fix your machine. Or you could easily copy files on/off your machine at firewire speeds.

In comparison, PCs in that era were always troublesome to administer, requiring disk cloning software or sometimes linux. (although they universally boot from USB now, which helps)

[fzzzy]

Target disk mode over thunderbolt 2 and 3 is also supported by the relevant mac hardware.

Target disk mode is also supported on mac laptops that are older than firewire; the original target disk mode is over scsi and is supported by the first powerbooks, the powerbook 1xx series.