I'm pretty sure that the commenter was being facetious, but I have worked at a company where they actually did this. They always had job openings posted on their website, and they would bring people in for interviews, even though they weren't hiring and had no positions to place those individuals in. I remember the CEO said "that way we'll have a pool of candidates to pull from if we decide to hire someone".

Needless to say, I never referred any of my friends.