What veehickle ever used that arrangement?     .

Look at the pictures of the trucks again. They all appear to be heavy haul or off road trucks where the tare weight is not normally a primary concern.

You can use it as long as you aren't powering wheels directly with it. Transports use it for refrigeration and to run APU. Why can't I use it to re charge battery then? 

Yeah I never bought into the traditional hybrid.  Too complex.  Why pay for the transmission, driveline and then electric motors and battery on top of it.  Too many parts.  Not sure anyone has the answer.  But definitely interested in seeing how this ram does.  Hopefully it isn't a flop like the Ford lightning turned out to be.    

Not arguing any of that. My boy has a plug in that is relegated to around home, and a hybrid that goes anywhere. It does well on milage as I understand it. Not just in town, but out on the open road it does somewhat better than an all gas version of the same {I think}. As you say - the camming and whatnot for gen-set use may be a big part of that difference.   Hybrids don't have much battery at all, compared to a plug-in. More like a capacitor I think.   .