The lower starting points of their respected MSRPs is not where the volume is, it's at the middle and higher levels of the MSRP where they are all similar. This is where the incentives matter, and Stellantis is trying to keep that down. Factor in higher interest rates where even 800 scores don't get great rates, and you have a recipe for lower sales.
Simply put, RAM has always been the truck with the better deal, sometimes you were buying the deal and not the truck. That has changed a bit with the DT generation, but people still expect incentives, especially if both GM and Ford are offering them.