Right, they just want the "regular" DexronIII/Mercon used. Since MB thinks so highly of Mobil1 (re: the stickers in the underhood area of the newer cars and the "Mutual Respect" ads in the auto magazines), they probably "would" recommend it, but don't want to go through the testing process on cars which are 5 years old, minimum. Believe it or not, all the brands of fluids they list have gone through a qualification process by Mercedes-Benz to be on the approved products list, same with the recommended tires. Just because a product is not on the list doesn't neccesarily mean it's no good, it may just have never been tested.
Someone can help me out here, but I believe the first year of the 722.6 (electronically controlled transmission) was 96, but only in the top line cars, like the s and SL, and was introduced to the other car lines gradually. I believe in 98 they all had it. The 722.6 cars all have the "S W" switch on the shifter, that's the easiest way to tell, and MB sells a fluid just for that trans.