The other advantage of true hunter/gatherer activities is that their physical nature allows people to rotate in and out of roles naturally.

If you are walking in the woods, everyone has down/slow days. Hiking/climbing groups know this and so rarely have dedicated leaders. Look at the military groups that occasionally climb mountains (ie wounded warriors on everest). On day one they throw the entire "rank" thing out the window. They know it doesn't work for mountaineering. Instead decisions are generally made by the person least tired/hungry/dehydrated at the time. That's how a hunting party would work: If Bob's got a sore foot today, he isn't going to be the one flushing the deer and instead might be today's planner/leader.