Originally Posted by Hohenheim of Light
That's really vague. For example, if you get proper nourishment after a workout, you'll be considerably less sore than if you don't. That doesn't mean you're gaining more without proper nourishment. Seems obvious but focus on the workout and the nutrition and not the degree of soreness.
I'm assuming everyone takes a good protein-rich meal/ a protein shake and a hour-two later carbs after training, but if not I guess one could get more sore than without training as the body will be "starving" for energy hence the reduced regeneration rate and added soreness, although you need to eat all the time (every 2-3 hours) nonetheless.
Soreness signalizes that your body is changing. I always try to push myself doing an extra set, doing some extra help reps or reducing pauses, basically increasing intensity in each workout. To grow muscles effectively this is needed, you can't lift the same weights, doing the same reps, the same number of sets and having the same pauses training session after training session as this basically means you're not making any progress thus not gaining any strength and muscle, you're only mainitaining the muscle you already have that way.
Even professional bodybuilders, powerlifters and olympic lifters feel sore after training so basically if you're working out right, you will never get past the soreness state. You can still improve without getting sore by training lighter, but the effects will be MUCH lower and it will take much more time to reach the same results as when going all out.