In the case of Hazley, it's just a speed and endurance event on hiking trails. In Hazley's case he had to average 50+ miles per day; on my best day I couldn't do this on level ground with no pack whatsoever. I wouldn't consider this backpacking either, certainly not in the traditional sense, but the speed and endurance of the feat is rather remarkable. Not my cup of tea as speed is not part of my nature.
From a gear standpoint Hazley's choices are largely irrelevant for most traditional backpackers. To accomplish the feat, Hazley would need to be resupplied often such that weight would be the only consideration. Also pack size could be quite small as he would not need to carry many days worth of food or repair items or safety items or spare cloths. Should Hazley lose or damage or wear out a piece of gear he'd simply be resupplied on the fly. Sponsorships also play a part in the gear that gets used. For all we know ULA was the only pack maker offering a sponsorship (I'm not suggesting ULA is a bad choice, but we don't know what went into many of these decisions).