No the problem is the same with anything really. If you get a base 2wd vehicle with no options you get better payload.
A Laramie Limited or Laramie Longhorn with a Hemi only has a payload of 1084lbs. It is only 881lbs on the Diesel.
It is simple, the heavier the truck with options the less you can have payload wise.
Now you see why I tow a 7200 pound trailer with my Jeep over a half ton... I can bring my wife and dogs