Well, I don't know you reached that conclusion, but it kind of highlights my point; if the defender doesn't know that the attacker is offside or not, and plays the ball as they clearly can't roll the dice on the offside situation, the attacking player will benefit from the offside position by forcing the defender to make a decision, thus interfering with play.If this were true then the rule wouldn't be needed if all it took for a player to stay offside is a defender knowing the striker is offside?
It should not be the players responsibility to keep tag on who's offside.