I would not make that statement. I was on the Mariner OTS in June and the main dinning room food and service was top notch. Is the food AS good as in the specialty restaurants? No. But if it was who would pay extra?
I do recall making the statement that RCCL's main dinning room food is about par with CCL's food, but that just means that CCL has improved in that department over the past 5 years or so. (I'm not sure that would be true of CCL's food in the past)
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007