I'm guessing here a little bit coobie, but I think John Deere is trying to ease the diesel owners into paying a little more attention to the low sulphur fuel, and in the long run you can expect your diesel to last longer using there additive. John deere does a lot of testing and they aren't going to make public what they find in a lot of cases but if they are saying your diesel will run better or last longer they might know something we don't.
You can take a look at the two parts in this here
John*Deere Fuel Solutions JohnDeere.com
They actually tell you about the low sulphur fuel and wear but the gasoline additive doesn't address it like the diesel. Maybe they are trying to tell us something.
Rob