There isn't enough information to conclude why this Titan got stuck the way it did, but it looks like it was a two wheel drive Titan with the Cummins engine. The tires don't appear to be the all-terrain version, which probably would have helped. Towing a moderately heavy trailer up a steep dirt road with a two wheel drive truck usually isn't going to work well. I do wonder if the WDH was still attached when the owner tried to go up the hill. In a 4x4 truck I would say keep the WDH on and configured so that the front axle can get some traction. But on a two wheel drive truck I would be inclined to disconnect the WDH bars so that all the weight is on the rear wheels for maximum traction.