MarkB
Legend
Except that PHysical, athletic skill challenges are a category of skill challenge. Climbing a cliff, trekking over a long distance, etc, are purely physical challenges.
Just like you have mental or social challenges, where the physical skills don't play a part. Athletics, Acrobatics or Endurance aren't useful in a diplomatic skill challenge. By your reasoning, then it's not useful because it doesn't have "hooks" for the physical character.
Open your DMG to the skill challenge chapter, and look at the skill challenges presented. See what skills they facilitate.
Trouble is, skill challenges as presented in the DMG suck. I've played through some of the early, DMG-style skill challenges in LFR modules, and they tend to leave half the party sitting around with nothing useful to contribute.
Later modules, on the other hand, either up the complexity of skill challenges to provide uses for a much wider range of skills, combined with room for creativity in applying other skills or abilities to the problem, or else divide a challenge up into shorter scenes, each favouring a different set of skills.
The more recent challenges are about ten times more enjoyable and interesting to play through than the ones which most closely follow the DMG layout.