Those are a very slick simple way to make a pouch out of kydex. The only down side to anything Kydex that flexes, is that it can eventually crack. Like holsters with wings, sweat guards, formed "clips" etc.
I've used the Comp-Tac single mag pouches for a long time, and a while back got into a deal for four or five of them in a package deal with a Glock I wanted. Adjustable for retention, and fairly simply made from one piece of kydex. They are not the best concealment wise, but they stay secure on a belt, despite being designed to slip/clip over the top. The bad news, is that if you don/doff them by snapping them over the belt, instead of threading them on the belt like a loop, you will eventually cause a stress crack across the top of the formed kydex loop/clip. I've busted quite a few that way over the years, so I try to thread them on if at all possible.
Originally, Comp-Tac used formed Kydex clips for their C-TAC holster, and they would get the same cracks at the top of the belt loops/clips. I broke quite a few of those too, over the years. They eventually went to an injection molded clip with a flexible plastic that wouldn't crack. Awesome upgrade when they went to those. I carried in a C-TAC for a very long time. The original holsters were better, IMHO, than their current offerings, other than molded clips. They were basically hand made, and very smooth, while also being well fitted to the guns. Some of the changes they made when updating production to CNC'd holster forms etc, resulted in holsters that were more pointy and pokey in places than their old ones.
Since I've started carrying AIWB, I've been using a JM Custom Kydex mag pouch ( the long adjustable one) and been pretty happy with it. I keep meaning to try one of his standard AIWB pouches, but have not placed an order recently.