That's because at a conceptual level, a "general purpose computer" is far from an ideal device for rent extraction. If your user is stupid, they won't be able

That's because at a conceptual level, a "general purpose computer" is far from an ideal device for rent extraction. If your user is stupid, they won't be able to manage a general purpose computer but will instead require a well-controlled computing appliance that will dutifully collect all the rents its creators can get away with.