Ah, good point, but take note of my 2nd example. Sniping.
During the Vietnam war, the Viet Cong and NVA would hide snipers in the trees to pick off infantrymen. Today, sniping is a widespread method, because of Vietnam. This civilian hunter is making use of trees aswell.
Using animations and stuff, we may stick a sniper in a tree and make him visible. It's not like he'll be hiding INSIDE the tree :P