A couple of posters mentioned that in here. I was surprised to see it. I did learn that it has a limited or no impact to your FICO.
My understanding is that since reporting rental history is so new to the bureaus that FICO has not been able to add it into the algorithm. Experian wants to report it because they want to have the most information on you. The more information they have the more people who will trust their reports. The more people that use them the more money they make.
I think I also remember them saying that they are only reporting positives right now, but soon they will add the negatives.