I tow a 33 ft camper with a 2020 2500, previously with a 2019 1500.
With the 2500, I tow locally (including a few miles on a 65 mph freeway) with a bare ball mount hitch, and beyond local with a WDH with a friction bar style sway control that came with the hitch.
The 1500 always swayed despite the WDH setup. The 2500 on the ball mount has very little sway, I do have the electronic sway control but I don't know enough to say that is why. It may just be I felt every little thing in the 1500.
Regardless, I'm going to use every tool available when I'm towing long distance because it won't make things worse. The only reason I do the ball mount locally is because my truck stance stays within spec of where you would set the WDH and it's a lot of work for a short trip.
tl;dr Doesn't matter if you NEED sway control, it's always a good idea.