You've got my thinking... which is good.
Try this on for size.
It's more important to address player agency/PC concept/build when describing their
successes rather than their
failures.
OK, using the two riders and everyone's favorite gorge, keeping in mind what I wrote above.
Assume two PCs are attempting pursuit on horseback. One is a skilled rider, the other isn't, but is very familiar with local geography.
If the skilled rider makes their check, it makes sense to describe them as succeeding because of their horsemanship, pushing their mount, etc.
If the unskilled rider who knows the lay of the land makes theirs, it likewise makes sense to describe their success as finding a shortcut, avoiding hidden obstacles, etc.
In both cases, this reinforces/supports the character concepts and chosen method of shaping the fiction. Obvious, right?
Now consider failure.
To me, it makes perfect sense for the skilled Rider to get stuck at the gorge --
precisely because they doesn't know the local geography. This makes (more) sense in the fiction. The rider rode as hard as they could, because that's what they do best, but, unfortunately, they didn't know the land.
Likewise the unskilled rider -- it makes less sense for them to get lost/forget an important terrain feature. It makes more sense for them to
fall off their horse (or overtax it, whatever).
Reifying character concept and acknowledging player agency
are important. But the place to do (most of) it is when a player makes their roll, not when they blow it.
To do otherwise would produce an... oddly un-simulative game where skilled people only fail because of their expertise (and not extraneous circumstances and/or the things they actually suck at).
To my mind, this approach does a better job at supporting player agency. You succeed because of your chosen shtick. You fail for a larger pool of reasons (which can include screwing up your shtick).