That's bullshit. While there is a large amount of stuff prepared offsite, it's mostly the stuffed pastas such as ravioli, tortellini, manicotti, etc. Pasta was always boiled in large batches throughout the day so generally only sat around briefly, many sauces were made from scratch, and all of the soups were made from scratch. For example, there is the "zuppa e toscana" soup, which consists of sausage, cale, and thinly sliced potatoes. Every morning they took raw potatoes and sliced them all, tore up fresh kale into smallish chunks, and ground the sausage. It always impressed me how the walk-in was almost entirely filled with fresh vegetables that got delivered every morning. They had huge bins of raw eggplants that they would cut up, bread, and fry for the eggplant parm. It definitely wasn't brought in prepared and reheated.
Granted, maybe this has changed recently, but I worked at Olive Garden from 2004 through 2009.
*Edit* Hell, they even made lasagna from scratch every morning, and that is definitely something that requires a lot of effort and prep time. In addition, they never froze it and reheated it the next day; we used to give the leftovers to the local police officers.