Since we're doing superficial cliches, the best defense is a good offense. So, even if defense truly wins championships, then the best defense is a good offense.
The Saints during the era of the Dome Patrol had historically top level defenses. They rarely made it to the playoffs and they never won one.
What wins championships is a solid, well balanced team and some good fortune with the uncontrollable factors, like the literal bounce of the ball.