100% self sufficient is not the same as 100% prepared. Of course nobody is ever 100% prepared for 100% of all conditons. Self sufficiency is simply that you do not materially or mentally expect "support" from others. In other words, you are totally comfortable if you never saw another person the entire trip. I would not underestimate the psychological comfort, particularly for beginners, of knowing others will occasionally come along. It takes some experience to be psychologically self sufficient. And you are totally correct about skill and judgement being as important as gear. Self sufficient people do ont "borrow" or lean on others skills- the have thier own.

And you are correct, the better question is do you ever depend on the "trail community". I know PCT'ers do, even if simply for occasional companionship, beta, and moral support. Would a PCT'er pack or do anything different if they KNEW that they would truely be solo for the entire trip? Would some of the later hikers even succeed if not for the trail breaking through snow that others do. I am not making a valued judgement, pro or con on this. The only problem I see with "planning" on material support is what if everyone thought the "other" guy would have the first aid gear so nobody had any! A lot of people nowadays seem to be solo backpacking in a loose "group" who are all heading down the trail. You get the social experience without the responsibility or dealing with another's different pace or style. For an "old school" hermit like me, I find this a little disturbing because I DO see a lot of people on the trails who seem to be ill prepared and highly dependent on others they do not even know. Along with this trend, is the use of PLB devices that seem to enable the less prepared to do something they would not otherwise do.