Depending on where you are hiking, sustainability can trump LNT. LNT is a more local ethic for high traffic and more sensitive habitats. Sustainability is a more global ethic. In less sensitive and lower traffic areas, a small fire can be better practice than most stoves, even alcohol stoves. By small fire for one, I mean basically a hobo stove in summer, and somewhat larger in winter, particularly when it is used only occassionally, as a hedge against extreme lows, or falling through the ice, or something like that. So with prudent use of a wood fire in such instances, and wood scrap fired stoves for meals and drinks and ablutions, they rest of you kit and practices can have less impact on the global environment, and still be sustainabile in the local habitat.

At higher elevations, and drier habitats, and higher traffic areas, I would not use fire. Here in New Brunswick, its best practice, if done right. Certainly much better practice than alot of stuff, like canister stoves etc.