Looking at the info available on the MediFast diet it was originally intended for morbidly obese people to loose weight quickly. However the diet was not intended to be used long term and was doctor supervised because of the extreme caloric reduction.
The diet in its current form sort of resembles it (from a calorie standpoint), but unfortunately really doesn't provide help with making long term sustainable food choices (unless you plan on purchasing there foods).
I think it will work because of the extreme calorie deficit, however I am a bit wary concerning the nutritional profile. I couldn't find any information regarding macro nutrient profile of the meal plan. It also seemingly contradicts itself by stating something along the lines of getting around 2K calories in only 1K calories worth of food. However it also states that the dieter may need to take a Multi to help supplement because their could be a deficiency in nutrients.
To me the last sentiment has me questioning what exactly is being used as "fillers" in processing? There were also some concerns over constipation which means you might want to add some sort of fiber to help supplement.
As for why they specifically forbid fruit I am unsure about. I know there was some concern in the Low Carb diet group that certain fruits were high in carbohydrates and since fructose is considered a simple sugar would also be high on the glycemic scale.