Does it frustrate you when people....?

YES! I can't stand that. I have seen too many parents who use it as a cop out so they don't have to comfort their kids. Put them in the crib with a pacifier and leave them because if they have that they won't cry. Never mind that what a baby cries for is human interaction and love, NOT just a plastic thing to be shoved in their mouth. And having it all day just because is bizarre. I know one baby who's parents constantly did that and the poor kid didn't even try to talk until he was about 3 because he always had it in his mouth.