For the original commenter to be wrong you'd have to argue that they've been underutilizing what's possible in the state of the art. Looking at the Wikipedia page, I don't get that impression. It sounds like giant engines and equipment on the terminal side are the main limitations, and I assume those capabilities have increased over time. Maybe the original commenter is wrong, although I highly doubt that cargo technology has been underutilized unless the cost of state of the art is/was truly so astronomical such that it genuinely doesn't make financial sense.