I would also say driver skill/experience.
I know a guy who took his brand new Navara around the extreme course at one of the Eastnor Landrover Shows, loads of people there with winches etc. He was an offroad instructor in the army. When they came out his son asked the marshall where the entrance the extreme bit was
A couple of years later there was a guy there in an 88" Series 3 with a Tdi who was one of only a handfull of people to make it up one hill. All the others were tricked out Defenders with air lockers,lift kits and big tyres. They featured him on LRO and he explained how he was braking with his left foot and so stopping any wheels spinning and creating the the same effect as locked diffs/traction control
I know a guy who took his brand new Navara around the extreme course at one of the Eastnor Landrover Shows, loads of people there with winches etc. He was an offroad instructor in the army. When they came out his son asked the marshall where the entrance the extreme bit was

A couple of years later there was a guy there in an 88" Series 3 with a Tdi who was one of only a handfull of people to make it up one hill. All the others were tricked out Defenders with air lockers,lift kits and big tyres. They featured him on LRO and he explained how he was braking with his left foot and so stopping any wheels spinning and creating the the same effect as locked diffs/traction control