Not sure if it's standard dealer practice on your side of the water but I don't think they offer it to us in the UK. I've read the same thing about putting it undue stress on the engine due to the chemicals used in the flush stripping out the remaining oil from the big end bearings. But then again I've seen people using it in boxer engines with no problems, as long as it doesn't contain parrifin it shouldn't harm it.
Modern engines with oil changes done at the correct intervals shouldn't need it as there's not as much build up of deposits compared to older motors,