Shoeing dead hooves is gross, grizzly, disgusting, and smells just terrible. It smells like a dead carcass, which is what you might expect it to smell like. You can not wash the stink off of your hands and clothes. It is nothing like shoeing live hooves attached to live horses.
It is true that a student can get the bare bones basics of trimming a hoof, shaping the horseshoe, and nailing the horseshoe to the hoof but it is so unlike the real life experience that little of value is gained from it. But for that matter, you could shape to a metal pattern and nail to a piece of wood so you would not have to use dead hooves.
The hoof does not move around like it would if it were on a live horse. This teaches the students body to move with the horse as he is working. This is one of the most important aspects of learning to shoe horses.
The hoof does not bleed if a nail is driven too close, so very little is learned from nailing onto a dead hoof. As I said, you could learn just as much by nailing a shoe to a piece of wood.
You can not see the horse travel before and after it is shod, which is really the essence of horseshoeing, how the horse responds to the shoeing job. You can not see if you have helped the horse travel better or see if you have helped some lameness that the horse might have.
When live horses are used very, very few nails are ever driven too deeply because students compensate on the side of safety for the horse.
The idea is NOT sound. The technique of shoeing dead hooves is used by a school because the school does not have the confidence of the horse owning customers who bring their horses to be shod by the students. Not enough hooves to shoe, ok then, shoe dead hooves.