Bigger the belly, bigger the deadlift. I know from experience. All strength sort of comes from the mid-point of the body. I never used a belt below 300kg but maybe should have (umbiguinal hernia). Strong "big" core with belt to support it further makes for the strongest
lifts. It's not an extremely technical lift but little tricks can add up to maybe even another 100lbs after you've seemingly maxed out, after muscle size doesn't increase anymore.
Doing some huge dead without a belt adds to the "bad ass" image of a strong dude. Invariably bystanders will say, "man why don't you use a belt, is that really safe?" No most cases it's not essenntial by any means, just like knee wraps aren't essential to big squats.