V8 cams have been lubed by splash lubrication pretty well since the day of inception,and the Hemi is no differant.The leakage past the lifter bore is not enough to lubricate the cam lobe or the wheel,with-out some extra help from the oil flung off the crank. The cam/lifter issue didn't rear it's head till they moved the cam tunnel up,and blocked alot of the crank splash with the tunnel for the VVT system,which should lead you to the idea the cam lobe and roller are still relying on splash lubrication to maintain an oil barrier on the face of the lobe and roller. If your theory worked,after they increased the bearing diameter in the roller,there should be no failures,but there's still a pile of 16+ trucks and cars chewing up cams. Up till 08 lifter failure was basically unheard of,that's when the cam tunnel was moved up,and the VVT passage was added,and that's when the cams and lifters started going south.Only change was the fact the cam now gets less crank splash .The cams metalurgy didn't change when they went to the VVT system,but cam failures went through the roof.