I believe evidence points towards absolute level of fat being more important than % for overall health.
E.g. 20% bodyfat at 250lbs is still a lot of fat.
Of course it's difficult to ever get very high on absolute fat if at 15% or below.
Its not just absolute amount of fat though you also have to account for intra abdominal fat being much worse metabolically than subcutaneous fat.
Do you have a citation for that? I've had thoughts in a similar direction (specifically around the upper/lower intervention points) but have had no luck finding data.
Does that have to do with sizes of the heart and few other organs apparently being largely constant regardless of height?
Not sure I follow the logic here, but happy to be proven wrong if I'm misunderstanding. It's not intuitive to me that a 300 lb. person at 20% body fat is generally at the same risk as a 200 lb. person at 30% body fat.