Huntingdog,
If you knew how many 15-25% local road grades one has to go up here in the Puget sound region, you might figure out why a person would come up with a 30%grade want. No different than folks on here saying reduce max tow by 20%.
Forest service roads have no max limit like interstates at 6%.
My sister lives on an 18%grade.
People do drive fully loaded trucks with trailers thru Seattle, I'd be 50%of the roads are 15% or steeper.
A perfectly capable RV pickup as you say, needs to work for those in construction, delivery, grocery getter etc. Ratings are one size fits all.
I have stalled an older truck out with my RV in tow in 2wd when it should not have stalled out. With in gcwr mind you.
I have MY definition of min performance of what a truck should do. I have no problem saying, the current spec is lower than my mine.
My performance spec is really no different than one needing proper wieght ratings for payload needs etc. Just another, will this truck work for me. You should be doing the same! Demanding actual specs saying the truck you buying will get you from point A to B on what ever type of road you drive on.
Marty