Watch a few videos on youtube of AT thru-hikers documenting their journey and you'll get a better sense of how something like this could happen. Most try to go so light that they carry ZERO survival equipment. They carry a shelter and enough food to get them to the next town. That's it. I've seen posts on WhiteBlaze.net where they actually ridicule people for carrying a knife, compass, or fire-starter because it's "useless dead weight". Most thru-hikers carry less gear than I have in my pockets to go to work in an office.
I work with a guy that's thru-hiked the AT and he labels anyone who he sees on the trail with a belt knife as an idiot neophyte. Thru-hikers are no doubt a tough bunch, but they are definitely a different breed. They can lay down 20 miles a day, day after day, as long as it's on the trail. Throw most of them out in the woods with no marked trail and a lot of them would be just as lost as this lady was. They're not hunters who willing venture off into the unmarked wilderness like most responding to the thread. Of course, there are exceptions to every generalization.
I'm guessing her age and anxiety, along with the obvious lack of woodsmanship, played a large part in her demise.
