iserith
Magic Wordsmith
I think it's about "things on a sheet" versus "things not on a sheet"
Example:
DM: You are in a room. There are no exits you can see as the large stone door you entered has shut tight, seemingly of its own volition. As you look around you see figures in bas relief on one of the walls and a number of skeletons on the floor.
Player: My character tries to deduce the answer to this riddle. (Or "I want to make an Intelligence check to solve this riddle.")
DM: Okay - roll an Intelligence check.
^ Here, rather than "challenge the character," the DM has simply removed the challenge altogether since no skill or choice was required to overcome the obstacle. Which is why "challenge the character" makes no sense in a nutshell.