I assume you meant the DH takes away strategy? But I think your terminology of "very small amount" is pretty objective. Having the pitchers bat causes you to handle defense differently (pitch around the 8th hitter or not), offense differently (bunt or not with the pitcher, pinch hit or not for him), who to double switch for if the pitcher spot is coming up, and it allows you to use more bench players. I think overall it affects the strategy more often than just every 9 ABs if you include these other factors. With the DH you can just leave a pitcher in until you want to pull him without weighing when he will bat again or if letting him bat outweighs pulling him for a pinch hitter.