I think suspension is definitely a factor. Obviously, lots of factors involved. But from a practical perspective, this was the first limiting factor when I loaded up our 2018 JLU Sahara (OEM suspension, no lift) for our first extended camping trip.
I actually built a spreadsheet for weight, and after roof rack, RTT, gear, food, water and humans, we were right about 1,200 pounds of payload. Close to the max payload. Rear springs were a bit too squished for my comfort level. I installed an Air Lift rear air spring kit for about $100, and the Jeep was level, much more planted/safe, and we were on our way.
BTW, I’m working with a dealer now to replace our 2018 JLU Sahara with the new 2021 JLUR 4xe. Can’t wait for the added HP and torque. Will use it for my commute to work using mostly electric power. The $7,500 tax credit makes the net cost about $4K less than an identically equipped non-hybrid Rubicon. Impossible to justify the ICE version in my use case.