Thanks for sharing this here, it really does appear to be the primary culprit. If anything the larger the vehicle the more fuel efficient it should be, not the opposite.
But that is just one part of the puzzle.
The other is of course just normal marketing, advertising, etc. convincing people that they do lots of things outdoors that they don't actually do. Ford, GM, Toyota, Dodge, etc. are not the only ones guilty of this of course as Patagonia, REI, Apple (Ultra watch), and other companies that tout the Great American Outdoors have suckered us (me included) into these outdoor lifestyle brands as well. They all make fine products, of course, but people who tend to want trucks want them because of what they think they enable.