Quote from the PCP Guide 5
(It is about the fact that the less the source code of the page will see the user, the better)

* the note *
Per you’ll ask with your eyebrows: "What, from a programmer’s point of view, is a good user a blind user?" Then we’ll answer: "What are you, no and again no! Such a user is good only for the designer, and for the programmer is desirable a user without hands (or at least without a keyboard and mouse).

by Fakka