That depends, do you describe defending in terms of stopping play within a certain area or stopping your opponent playing in general. If we go with the later then everything is defending, running towards the corner flag is defending because it denies the opposition the opportunity to create an attack.
I actual think you may be supporting what Conte has said. By you logic, Barca don't traditionally 'defend' then, the 'tracking back' is the traditional interpretation of defence, maybe Cone meant what you said, that if we are fit, keep the ball and do everything to win it when we lose it whilst scoring goals we don't need a defensive structure. I agree with Conte, insofar as I believe that there are three parts to the game, Attack,Defend and Control. Barca control but they aren't the best defensively, they don't need to be, because if you have control you don't need to defend.