You aren't painting a fair picture. RFSoCs cost more but they also have much more dynamic range (both amplitude and temporal). It's just just about configurability, but also performance.
You really are proving my point. Based on your misuse of nomenclature its obvious you're not a HW guy. The ADC is the last in an RF chain and typically sets the systems dynamic range if you've done things right. There is nothing special about the ADC in the RFSOC other than the designer will not need to worry about creating a physical, digital interface to the programmable logic.
I don't even know where to start on your "temporal dynamic range" comment....