I daresay that while I don't always contribute to local economies when backpacking, my trip closet is filled with a buncha gear that cost too darn much - I'm contributing to someone's economy. And I guess that there are plenty of local economy possibilities for folks - witness the place in Monson which is THE place to stop, eat, and sleep. There are many such places along the trail.
Backpackers impact on the environment is pretty small in comparison.
I've been there twice. Truly extraordinary, something worth keeping a little bit wild. I want my daughter to see it for sure.