I think that you're correct. I feel like its a difficult situation for a lot of reasons. 1) Packs are, like boots, a very different fit from person to person. 2) A lot of folks, if not most, are buying their packs either online or over the phone. This is a huge problem because, while someone can "walk us through the process" on the other end, it is totally different when you're having it adjusted in person. Its like someone telling you how you should lace your boots over the phone but on something far more complex. 3) A huge part of the problem just from personal experience is people thinking a pack fits fine but in reality it is nowhere near a proper fit. Think of how many instagram photos you see of someone talking about how great a pack is and the load lifters aren't even tightened down.
There is no denying some packs fit some bodies better than others. We all have unique torsos etc. I think the best thing someone that is buying a pack can do is before they do it, go to the place they are interested in, try a few styles and/or brands on. See what they are like with 35+ pounds in them and walk around, and have someone who knows their stuff walk you through the process. Depending on where someone lives, there are usually some options, even if it means a long weekend getaway with the wife...or even scheduling a western hunt around trying to pick up a new pack. I bought my MR metcalf a couple of years ago and intentionally hunted elk that September in MT. When the hunt was over, I drove to Bozeangeles, and tried on several different packs in the greater vicinity (MR, SG etc.) I had help getting the packs dialed and was able to really check the fit. There just isnt a way to do this with detailed help over the phone or on a video.
To me, packs/fit are such a big deal that it is worth making an extra long trip to get it right. A pack is an investment in your hunting and, even if it means you have to wait a year or so, its worth getting it right because it is something you will have on you for years and years to come (hopefully).
Just my two cents.