With deadlifts, you going to want to keep your back straight and prevent from any kind of rounding of your back. Belts help with that. If you find yourself rounding with your back, that is more of a Zercher deadlift, and really is putting more work on the upper torso than lower. Stiff legged is the most prevalent way to deadlift and produces the best gains. As everyone pointed out earlier its just a matter of preference. I use belts and straps on real heavy days, and also when I am going for PR's, upping the weight, ect. Once the fibers, agonist and antagonistic muscles get use to the new weight, I will then go strapless and belt less.

To piggy back off of Dominic here, which is about as solid of advice as it comes, I would do the rotation and ladder effect. You for sure want to build up all of your stabilizers and supporting muscles. As Dom pointed out, the deadlift uses just about every major muscle group in some form or fashion. Even chest has applied constriction to it. Belts are designed to improve lift posture and to restrict uneasy movements so that the full isolation can be applied to the muscle group being worked, which in the deadlift is back as primary. However, using offsetting belt and beltless will cause shocking to the muscle fibers and give you the highest results so long as ROM is achieved without having to resort to bad form.

I use belts as they aid considerably with both the concentric and eccentric movements. The whole idea is to use strict and proper form all the way through the full ROM. You want to be able to really pin the back muscles, utilize the stabilizers in your legs, quads, and upper body, ect. Any linear progressive periodization program should be centered around 3 principles. One is form, two is consistency, and three is change. Shocking the muscles fibers is what causes growth, so if using a belt gives better isolation and control through the lift, I would say go for it. You can go heavier as you dont have to use antagonist muscles to stabilize and balance the weight. Belts aid as they allow for progressive overloading to go much heavier. I would suggest doing both. Use the belt for a few sets and reps, and then do some without. Adjust the wight appropriately so your not substituting out form and control to get each lift up. Since dead lifting is using your entire back, traps, hamstrings, calves, quads, and erector, you just want to ensure that you use good control