And OP you’re getting some halfway true info here. Better than the article but still some confusion in the responses.
If you wanna beef up the rear suspension a little just add whatever devices out of the plethora available that you think will work best for your scenario.
IE if the truck only hauls heavy occasionally you may want bags so you can dump them. Or maybe sumo springs.
Or if you haul heavy primarily then you may want something that adds capacity all the time like an overload or helper spring.
And the right shocks help a bit with ride.