First off, great thread! I love talking backpacking and climbing.
I began backpacking the the 70's with my dad. He was a police officer and most of the time when we went backpacking it was in the Sierra Range with his fellow officers. Pretty much everyone carried Buck 110's or something similar from Case, Camilus, etc. My dad and I carried Puma lock backs; I think my dad got them from the evidence room... . His was actually called the "Backpacker" because its handle was zytel, or something like that. I still have mine, a wooden handled "Deer Hunter" model. Nobody ever carried a fixed-blade; way too heavy.
I first started seeing SAK's on backpackers in the late 1970's and early 1980's. Not sure what they were called back then, but they were the models we now know as the Climber and the Explorer. To a certain extent, I still see these models in the backcountry to this day. You could buy them in hardware stores, Sport Chalet, etc.
Spyderco's seemed to come on strong in 1980's as well. They were new, had that one-handed opening feature that we hadn't seen before, wicked serrated blade, etc. Back in this time, Southern California actually had cutlery stores, and this is where you'd go for a Spyderco. Maybe Sport Chalet too.
In the 1990's the Leatherman, and its progeny, seemed to be everywhere. I started to see less and less of the Buck and Case hunting knives on backpackers. Mostly either some form of multitool, or some type of one-handed folder. That still seems to be the case today. I mainly backpack in the Sierras and the mountain ranges around Southern California; most people, even backpackers, give hardly a thought to their knife-choice these days. It's an afterthought, something to satisfy the "ten essentials." Around these parts, still nobody carries a fixed-blade. They see it as too heavy for trail hiking. When I carry my F1 on backpacking trips, most people think I'm a newbie that just doesn't know better!
I started climbing and mountaineering in the mid-1990's. Climbers are an interesting breed. They pay very close attention and develop almost zealot-like opinions about certain gear, like cams and dyno rope. Knives, not so much. Most just carry something cheap. The most significant feature for a climber's knife is lock to keep it shut, so it doesn't open in your pocket as you climb, or open in mid-air if it works it's way out of your pocket and falls mid-route. This is why I stopped using my Griptillian for climbing. There are a few knives built specifically for climbers with this feature. If you charge more than about $30.00 for your knife, though you're going to eliminate most of the climbing public as a client base.
So, that's my recollection of knives, backpackers and climbers over the years, at least in my neck of the woods.
ERG