It is the disconnect between character knowledge and player knowledge. As a player, I don't know how to use a sword. That doesn't affect how well my PC fights. I do know how to use outdoor first aid, but that doesn't mean my PC can heal others. A player who has a silver tongue might be able to fast-talk someone but their 6 CHA character can't. A player who is excellent at mechanical engineering might be able to disarm a trap, but their character might not be able to, and vice versa.
Puzzles violate the disconnect for the purpose of keeping players entertained, rather than just rolling "Disarm Trap" and moving on.