Comment by ryandrake

It's unexpected to anyone with intuition about how a computer traditionally is supposed to work. As a general principle, as a user, I expect a file on one computer to be usable on another computer. Or, at the very least, if I need to obtain some other thing from the original computer to "unlock" that file, I should be able to do it. The idea of a file that is only usable on a particular computer feels weird.