Yes, I'm hoping he addresses some of the points I brought up about the narrative he provided...
Hey, happy to do so!
Cool. Though it still doesn't address why a competent person can't slip and fall when climbing... or why that happening is inherently "silly"... or why this isn't just as silly... "DOPE!!! (headpalm)that goofball just loosened the brickwork for everyone else... even though he's a "competent" climber...
It's an example of a partial failure - which I used for two reasons:
1) It addresses the dissonance between the skill challenge DC and the climbing DC - i.e. the idea here is: the check was good enough to climb successfully (=> no falling), but not good enough to work towards the end goal of the challenge of the entire party moving across (=> brittle wall means no progress, since it hinders the following PCs) - while giving new material to riff off (=> following PCs could do something about the brittleness, i.e. more skill uses). Has nothing to do with silliness.
So the fiction is being forced to conform to the mechanics... every wall the PC's encounter as part of a skill challenge has something different about it that makes it harder to climb than a regular wall... Uhm, ok... this doesn't seem far fetched, but slipping and falling is considered silly.
Again, nothing about silliness. And fiction is always forced to conform the mechanics, it's part of rolling the dice and "rolling" with the outcomes so to speak. That isn't different from having a fighter deal 9 damage to a level 1 orc (instant kill) or 9 damage to a hill giant (a light flesh wound at worst). The rolls inform how the fiction works out, whether the 9 damage strike is gutting an enemy or barely scratching it. The fiction what "9 damage" mean warps around to fit the mechanical outcome.
You realize in this narrative he didn't fail right? He actually succeeded in traversing the climb... You also realize from a mechanical perspective the chances for anyone else climbing are still the same, not any harder, even though you've decided to change the fiction of the wall (I guess now fiction and mechanics are separate)... if the brickwork has been loosened why is the DC the same?
In the narrative he didn't fail the climb (as according to the DC 15 for a wall), but failed the goal of the skill challenge (making it across the chasm with the
entire group). The DC isn't necessarily the same, you can, as DM, rule that Athletics are now a harder DC (in fact, that's a point about repeated skill use!). Plus, the end objective (group crossing chasm) is harder overall, since you have less margin of error now.
Refresh my memory again, where in the 4e core books does it state that "failing forward" is necessary for SC's or even a part of the game proper...
[MENTION=42582]pemerton[/MENTION] had the relevant quote, though to be fair calling that principle of interesting consequences instead of outright failure "fail forward" is terminology I've cribbed from 13th Age.
Skill challenge are a bit of a shift in frame of mind - you need to think of them not as a collection of several skill checks, but a larger challenge - and success/failures aren't focussed on a particular task, but
overall progress (hence you can have "successes" that fail to contribute to overall goal and vice versa). Does that make sense? It also means, you need to cast them bigger than "cross a bridge", they need to be large in scope, just like combat encounters.
Additionally, you need to think more in real life terms: skill challenges
need the concept of partial failure/success. In D&D, skills are binary, either you ace the check or you fail. Things in reality are less clean-cut, you can have a hard climb, a narrow escape and so on. To run skill challenges successfully, you need to leave the idea of binary yes/no skill checks and have more graduated real life-like outcomes. Shifting that habit of DMing takes some effort, but once you "grok" it, it becomes quite natural.