Except that specific situation isn't happening one or two fewer times, there is one fewer faceoff wins on average per game, of those, a fraction is after an icing, and a fraction of that is against a top line and a fraction of those result in sustained pressure. And that's all assuming a huge gap in fo% of 58% vs 42%.
If everything else is equal, sure you go with the guy who is better on the draw, but what I'm commenting on is the hyperbole when it comes to the importance of faceoffs. A guy like Kastelic plays about 15 shifts a game and you're boiling it down to the importance of one, I'm more worried about their impact over all 15 shifts as a whole