It's all a balance. If you are slowing down for a corner by shutting off the throttle before the halfway mark on the straightaway instead of using the brakes (and yes, I've seen and heard it done that way on track days!) then yes, staying on the throttle longer and using the brakes up to a certain level is going to help. But pushing the ultimate limit of braking, with the rear tire just skipping the ground (and the bike on the verge of getting way out of shape), unless your name is Nicky Hayden, is going to make most people slow down too much and/or blow the corner and go straight every third lap.