I didn't suggest making a starter; but did get this idea from John Palmer years back off the BN. He wasn't asserting that this was best practice though but he did say it "would wake the yeast up". As it is this is not my own practice.
If it (the quart of wort) was showing some beginning signs of fermentation and you pitched this wort I can't see how it would harm the yeast since they are in a nutrient rich environment going into a bigger volume of nutrient. A big difference from a spent starter.
Conversely, I practice hydration and you must use dechlorinated water that has minerals in it. Tap water for most folks. Pure water is bad juju for re-hydrating yeast. You would still need to do this before pitching into any amount of wort. The "sprinklers" will of course deny that this has any benefit at all.