I'm an LLLL in suburban Boston and I do a lot of on-line support (BabyCenter, iVillage, etc.) as well.  We hear this a lot.  I wish I could explain it, as I'm not sure what people think every other mammal in the world does without a pump, not to mention humans before now.  I have heard it recommended for two reasons.  First, as you say, it supposedly helps bring in the milk.  Second, it's "just in case you have to supplement if baby has jaundice or loses too much weight."  Of course, it tends to go along with, "Feed on demand, about every 2 hours for 20 minutes each side," so it becomes a self-fulfilling prophecy.  But that's a different story.

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