Long time reader, first time poster. Question: Why buy holsters with a mag carrier built in?

Take a look at this guy's setup as an example. I see a lot of these kinds of holsters on the market from different manufacturers and for the life of me cannot figure out what purpose it serves. For my setup, I use an Alien Gear Cloak Tuck 3.0 and sometimes the Cloak Mod paddle holster depending on what's up or what kind of outerwear the weather calls for that day, or if I'm just working in the yard or something similar. I also use the Kore Essentials X-2 reinforced belt. I just got my CCP earlier this month but have been studying and practicing and training for most of 2016 (hard to find good instructors and reasonably priced training classes in my areas).I feel this type of holster is a disadvantage for standard "strong side" draw. Your spare mag is in your holster on the opposite side of your body from the hand that is, presumably, going to draw it. If you need to reload, how are you going to get to it without putting your gun in your other hand or reaching across your body to get to it? If you're right handed, and carry at 4 or 3 (I carry at about 3) and you're a bigger guy, you may not even have the range of motion to get to it or be able to pull it because you're at a weird angle.Are these types of holsters used for cross-body draw? Doesn't that kind of introduce a whole other set of problems, such as muzzling everything else in the room on that side of your body, as you draw?I understand it from a price/value/convenience standpoint. You're ordering one thing instead of two, and sometimes at a pricepoint that beats ordering a separate mag carrier, which you may have to hunt around to find one that you like. Or to keep from building it yourself if one doesn't exist that fits your needs. Kydex is for sale on Amazon, and heat guns aren't super complicated. Maybe it's just less things to put on your belt when you get ready to go out, even at the cost of your IWB holster taking up more space in your pants. Right?I just don't understand why these exist, and why people buy them given the disadvantages being stronger than the advantages, in my beginner's opinion. I know it's all about what works for each person and YMMV, but I still don't get it. Please help me out here, because this is confusing to no end.EDIT: Now I get it. Appendix carry. I'd thought about these types of holsters before, but it was not clear to me that AIWB is what they were designed for. via /r/CCW http://ift.tt/2idLLZG