I think most people, including myself, get aftermarket shocks when the get or after they have larger tires. The stiffer shock helps control the heavier tires. So the two cancel out somewhat resulting in an OEM ride with the billies and 33s.
Maybe stock tires with bilsteins or almost Any aftermarket shock ride stiffer.
The OEM ride was pretty cushy.
You make a very good point, my 35-ish size tires need a lot more damping then a stock tire. My stock shocks must have been done when I took them off because my truck rode like a boat.