I like to collect old knives and I can only say that people have carried and used long knives, short knives, fixed knives and folding knives, thick bladed knives, as well as thin bladed knives, for centuries. It comes down to environment, available materials and techniques, and to having the right/best tool for the job. What was popular varies widely from location to location and culture to culture. A 3-1/2" folder might do-it-all, until you are confronted by a coconut; and while you can process game with it, it is certainly safer and more sanitary to work with a fixed bladed knife. A folding saw can process wood, but it would certainly not my first choice to hack a trail through brush; for that I would go with a machete, or even a bolo/golok/kukri depending on how heavy the brush is. We only need to look back on the industrial meat processing plants prior to automation to see just how many and varied the knives were.
Everyone has their own style of camping, and while "survival" is usually a vague term used to sell to the uninitiated, there are certainly issues there which can be considered as well. At one point western military doctrine relied heavily on using facines as basic building blocks for field engineering, and they usually issued billhooks or similar large heavy knives for that type of work. In today's zero impact, modern backpacking, there is little need for a knife at all. You usually pack in a self-contained stove, lighting and fuel, your shelter and bedding is prefabricated, your food comes in packaging designed to open without tools. When I carry knives in the wood, it is mostly for fun, to see what the various types of knives can be made to do. But you do not "need" a knife and all knives are certainly used-less than they used to be. But, it can also be argued that you do not "need" anything in life other than perhaps air, food, water, and some basic shelter. But having knives, and countless other things certainly adds spice to life. We do alot of things that are unnecessary and that is what makes things fun.
Enjoy your knives.
n2s