hmm..i disagree.
depending on the size of the tank, and how much rock you add, bringing rock home wrapped in some wet newspaper is not going to prevent some die-off.
unless you have a 100 gallon tank and are adding 15 pounds of rock, i'd put it in a separate container and give it a few days. check the water parameters of that container, and then you can be sure.
btw- i've seen plenty of local stores selling "cured" rock with all sorts of soft matter hanging off of it. alot of dead sponges and plants will most certainly cause some issues.