What it comes down to is who is having the most fun. I enjoy a technical climb, but like the vast majority prefer riding downhill, so I give way to people coming down
^^This, its so obvious. After all where not traffic as such on the trails, just people out having fun. I know this topic comes up for discussion from time to time but in 20+ years of mtb’ing, this up down priority thing has never been a problem for me, people just sort themselves out naturally without needing Rules to obey. Maybe that’s just where I ride, yet to meet a “I’m going up get out of my way” rider.