Beyond scenarios based on apocalyptic, and unlikely, 'running from authorities', or 'avoiding plundering hoards' scenarios, most of which are based on a misreading of reality and/or tactics, there are a few good reasons to maintain some ability to maintain a low profile.

IMO as more people take up hiking and camping the people themselves, particularly when they wear or use bright colored gear, become a form of visual pollution. When people use and wear subdued colors the situation seems calmer and less chaotic. A matter of aesthetics.

I also have been known to use subdued gear simply because people are social animals. I have found that if I set up a tent it isn't uncommon for people, particularly those who are less experienced in wilderness manners (exactly the sort who will be out in force after a major disaster) tend to try to set up right next to, sometimes on top of, my camp. Subdued kit and camp placement a bit farther off the beaten path than normal go a long way toward keeping people out from under foot.

On the other hand when you want and need to be spotted you need to have something that will stand out against the predominant background. Day-glow orange, blues, yellow and greens jump out at you. The military use identification panels with bright colors. A 2' by 6' piece of cloth in a bright color folded into a ground cloth, a bright hammock in the tent, or a distinctive sleeping bag liner are all options.

Generally there is little need for actual camouflage, Simple, and often less expensive, earth tones, dull greens, grays, and browns all virtually disappear once you get any distance. Deep and dark reds seem bright up close but once you add a bit of distance they appear often look brown or black.