But, lets say you only want to shoot big deer. The rattling may scare off young bucks unwilling to fight. That way there's no chance of thembusting you on your stand. I did a similar thing last year, Saw two forkies sparring about 40yds away, I didn't want them to approach so I did some aggressive grunting and they went away!
That being said I've also heard/read that the really old mature bucks may also not come in, many get that old by avoiding any confrontation. It all depends on their experience during their young and formative years.