Yes. A few of us have backpacked in the winter and at altitude. And obviously, others haven't.
In New England, once you're in the boreal zone (about 2500' and up) harvesting wood in winter just isn't practical or, in most places, even allowed. Technically, camping above treeline in the alpine zone (about 4300' and up, depending on wind exposure) is forbidden. It does happen, and everybody knows this, but it requires significant outlays in gear (tents and sleeping bags). 50mph winds and -20F temps are common place. Realistically, most folks camp just below treeline.
Winter camping in these zones requires that you have a clothing, shelter and sleep system that is utterly dialed in and most importantly, that you know and stay well within the limits of your gear. I've camped and slept at -15F but that's as far as I'm willing to go with my current gear. I simply won't go on trips with temps forecast at -10F or lower but feel very comfortable at 0F or even -5F. -10F is doable with a bit of margin for safety but that's it.
Central to any winter camping system here is the camp stove. Stove craft, which includes the ability to repair a stove if needed and to coax it to life no matter what your condition or the weather is a real and important skill among winter campers. People who lack adequate stove craft skill are a threat to themselves and others. People with good stove craft are an asset to any team.
Knives are a part of the tool system and should be regarded as such. Gear repair is the biggest issue for safe winter travel (including retreat). Using a knife for food preparation is not needed. Foods like meat and cheese can easily be pre-cut during pre-trip preparation. Pre-cut food are much easier to deal with when you are hunkered down behind a small rock outcropping and the wind is howling hard enough to knock you off your feet. Summiting a winter peak while crawling is common.
The small Leatherman is the most important of the two, primarily for the ability to repair equipment.