[btilly]

The point is physical security and information density.

If you use an electronic one-time key and then secure wipe, you're not protected from someone who unbeknownst to you already read the contents of your hard drive.

If you use handwritten papers then you cannot store large amounts of data, nor is your data transmission rate anything feasible.

This allows an uncopyable object the size of a grain of sand to hold about a terabit of private shared data, and to process that at the speed that we can send/receive/react to light. (Considering that the basic technology is also used to send signals down fiber-optics cables, speed should be pretty good.)