There may not be much point to seeing how long you can go on the AT without resupply, since so many resuppluy points are available - other than the simple challenge of it, if that's what you want. But there is a real point to longer trips without resupply in other situations. For instance: I would like to do a trip in the Sierra covering the entire roadless section of the crest - that would be roughly from the Tioga road in Yosemite to the southern Kennedy Meadows - no roads cross the crest between those. If I were to do a part on-trail, part off-trail journey through that area, it would be about a one-month trip. I can see a great value for me in keeping that entire trip free of contact with "the outside". So being able to do it without resupply would be preferable - in some ways. And worths considering. Essentailly, it's a way of getting to a different kind of experience. To be completely away from roads and towns and buildings for that long would be quite different from the experience you get on the AT in a month.