It's suggested that the Dweller actually wandered to the mountains without a ton of equipment, but with a bunch of other dwellers who helped him establish a tribe. As for the stuff about the Chosen One using computers, energy weapons, small arms and machinery, it's just extremely unlikely. The whole imagery of Arroyo evoked by the game to the player is an image of a primitive tribe with little experience of technology with their champion ready to save them. Ever see some of those still remaining tribes of Africa on a documentary perhaps? It's exactly like that, hunting being it's main skill with cooperation of its hunters efforts to capture prey for the tribes consumption. While they're not animals, they are primitive in that they rely on mostly primal instincts. Their ignorance as to the true meaning of the vault suit and pip boy only serves to illustrate their primitive nature of the world (just a jumpsuit all the dwellers wore and is nothing special, and the pip boy to mainly serve as a map and store objectives). Even with traders coming sometimes and trading maybe something in the way of computers (also unlikely), they wouldn't learn anything, it's like a powerful alien race visiting us and giving us powerful and sophisticated technology which we would not possibly learn how to harvest. Also add in the fact they have no plug sockets and you get the idea. I guess the only thing open to debate is the brotherhood armour as wearing the armour is juxtaposed to 3's and NV's way as you had to be taught to learn it. Of course in 1 you had to join the brotherhood to gain possession of the armour and thus learn how to use it so that raises questions as to how the Chosen One learned how to use it.