There is camping gear that is way cheaper and easier to carry. Like some tripod chair thing that folds to a stick. Why would anybody want this? And it looks like anybody who used it failed and sit on the ground a moment later. This world...
It just looks like an engineer designed it and there was no effort to refine it. As you say, a camping chair or a shooting stick would be better and as easy to carry and no harness and thigh straps. I get they were trying to have something that is convenient and relatively easy to carry around but even in the other videos you can see there are problems.
You look like a massive dick
You cannot swivel on it so you have to get up, turn, sit down, get up, turn back the way you were and sit down.
You look like an utterly massive dick
It looks like a rejected idea from a bondage/S-M shop
It is hard to emphasise enough how absolutely massively dick-like you would look