I feel like this goes back to player agency, by choosing riding I am letting the DM know that I want this part of the narrative, concerning my character, to be about using my riding abilities to try and overcome this particular challenge. However by creating a gorge that suddenly appears before me, aren't you basically taking away my power to steer and shape the narrative through my characters riding ability and instead made it about something else (the geography of the imaginary world perhaps)?
In the situation described the player failed a ride check, so I'm confused.
Could you provide some examples of failed ride checks which don't take away your power to steer and shape the narrative through riding?