Funny you should bring that up, because it's another topic I've been meaning to post about.

It's true. We are all a function of the terrain we have available to ride.

The distinction that Pablo makes, and it's one I agree with, is that some are simply after an aerobic ride through the woods. Anything that detracts from sustained spinning is seen as a detriment. I am speaking here of the "roadie on dirt". Whereas others relish technical accomplishment, the roadie on dirt is all about pedaling faster for longer--nothing more.

Technical challenges add spice to a trail. They also hold down speeds such that those of us who are less fit can still hope to keep the pace. Not that being less fit is desirable -- far from it! I just like the fact that success on a mountain-bike trail is not solely the product of a single dimension such as aerobic capacity.