If it was blank, it would be less reassuring. And the whole point of the "document" is to make the recipient feel more comfortable. It includes all the magic words specific to this "secret trick" that means you don't have to worry any more now that you paid us your money.

Until of course they try to actually use it for anything. Then it pretty immediately stops being comforting. They must have accidentally got one of the words wrong or something, so they order a new one that is slightly different because someone showed them that one and it for sure has all the right words on it and it will definitely work. You can relax again.