Perhaps it was to protect the user, not the machine. If you drop a spoon in, it might break the fuse before pinging it into your face? Or it might have been a s

Perhaps it was to protect the user, not the machine. If you drop a spoon in, it might break the fuse before pinging it into your face? Or it might have been a sliding contact that needed better wear performance than metal on metal, or it might have been an odd shape that was expensive to make from metal.