Why using a BOX, if you already have a PC?

I still do not understand. Having all the necessary hardware in a PC, why you need to use a box to flash a phone ?. It will be a matter of marketing Z3X, Octopus and other manufacturers of these boxes? With only develop the necessary software and drives, the PC is able to do the same. I do not understand why it has not been developed. The electronic content of these boxes are no more than a PC.

Comments welcome
If someone has a reasonable explanation! 🙂