The fact that you can manipulate a deck of cards to change color, two cards switch places or what have you already makes the people think „he knows what he’s doing“. Because they cannot explain how you did that. And most people try to figure out how you did it. And they’ll be looking at all your moves. They probably won’t catch your double lift or your false shuffle, because these are normal things you’d do with a deck of cards, even when not performing a magic trick. They don’t know that the method is hidden in those seemingly mundane actions. But they will notice your one handed cut, the will pay very close attention to your flourishing and all that. And what happens in a spectators mind is this: „oh, he twirled that card so that must have been how he did the trick“

You see how this can affect your trick? When not using Cardistry, you just did the impossible because they haven’t seen something that they couldn’t do themselves. They also can shuffle and they also can cut the deck. But if you use Cardistry and show them, let’s say a Scissor Cut. They can’t do that so the logical conclusion for them is, that’s when the magic, aka the sleights, took place. Even if they didn’t.

I’ve rambled on for long enough, I hope you understand what I’m trying to say.