And they want their nature presented with no or minimum manipulation (the likes of Peter Lik, Tom Mangelsen, and Michael Fatali).
This is where I call BS. These guys sell Cibachrome prints from Velvia chromes, that in many cases were shot with on-camera filtration (polarizers, grads, maybe color-compensating filters). Just because they're not using photoshop, doesn't mean they're not enhancing their photos. Velvia colors can be called a lot of things, but accurate is not one of them (not with a straight face, anyway).
IMHO, to argue that a Fatali/Lik print is more "authentic" or "honest" than a digital photographer using curves, saturation, even exposure blending to achieve the same end result is utter nonsense. I'm sorry but I just don't see how anyone who knows anything about photography can honestly argue otherwise. The fact that Fatali/Lik have used such claims to increase sales just illustrates how many suckers are out there. IMHO Fatali/Lik are being disingenous at best when making such claims in their marketing.
Now if you want to argue that their photos are more "authentic" than somebody who added or removed objects to the image in a way that misrepresents the reality of the scene depicted, then OK I can agree with that. But it's not fair to assume that such manipulations have occurred to any image that has had computer post-processing done (which is what the anti-digital folks will often imply if not argue outright).