AV, you can't continually say you don't understand because everybody you've asked has given you their reasons (see Chutch above and me elsewhere). What you object to is other people wanting to know something you have no interest in which begs the question "why don't you belong to a forum which deals with something you DO have an interest in"? I usually think I recognize an actor from some show or other and like to keep their CV's up to date.
Where on earth do you get the stalking idea from?? Were the people who belonged to fan clubs in days gone by, stalkers? Are the millions who follow major stars and want to know everything about them, stalkers? The closest I've got to "stalking" a performer is to go to their website (most don't have them) to get clarification about an ad/performance and they've always been happy to give the info and often grateful for the work done on CV's at the British Film Institute/ITNSource/tv.com etc...