Konrad's reply has excellent insights on the whole knife discussion. My perspective as a survivalist/bushcrafter that has gone the full switch to an UL/SUL backpacker made the whole knife thing a bit more complicated. My father always taught me how important a knife is, but as most military dads I would imagine, exaggerated some, and didn't really emphasize the difference between a "safe" experience in the woods and all out war/survival situation.
I used to always take a small axe plus a folding saw with me, as I primarily relied on campfires for cooking, as well as having the heat from the fire contribute significantly to my sleep and clothing system. After getting my base weight under 20lbs, and approaching 10lbs I began to test myself. I would take only my K-bar survival knife with me rather than my axe, saw, and small pocket knife--which would actually be a big savings of weight. I was able to accomplish the same goals with the K-bar knife, i.e. make a fire to cook and help stay warm (even before/during/after light rain, though this is a pain in the neck). It was inconvenient for other things, like gutting and scaling fish, so I looked to experiment more. I then found I was able to make smaller, solo campfires that would fit most of my needs at the time with a 105g Mora knife.
I have since mostly taken either a Mora or a Swiss Army knife with me, and find that I still use them quite often at camp, and every now and then on the trail. I have never gone knife-less, I just don't feel safe, and find it far too inconvenient as Konrad so aptly pointed out. Some may attribute my uneasiness at leaving a knife behind to Machismo (I have seen this specific word used here on BPL in regards to knives that are not considered light weight), and while this may or may not be true (nor do I care either way), it evades the issue of how pragmatic in reality it is to either take no knife or take a tiny less than 1oz/28g knife. When I have gone camping with people who take no knife, they often ask to borrow my knife for whatever reason, and I can't help but wonder if those that decry taking a knife larger than 1oz/28g would do the same if they were to go camping with me in my neck of the woods.
If you have a system that allows you to have a good time, be safe, and are able to complete all your goals with a razor blade or no knife--good for you, and I mean that without any sarcasm or spite. But please allow for an open discussion of the limitations of this system, and encourage you to move past this whole "Rambo knife sux lol" type rebuttal. I think we all get it at this point that a big 1lb survivalist knife is absurd for the purposes of ultralight backpacking in general. Yet the multi-use and practical nature of my 105g Mora knife was important/pragmatic enough for me to take it with me even on the few XUL trips that I have gone on.
EDIT: to fix typos.