I noticed a while back that in the lighter weight classes deadlifts virtually always exceed squat poundages. In the heavier weight classes the reverse is almost always true. I asked a friend who has done some powerlifting about this and he said it was because grip strength was the ultimate limiting factor in the deadlift, not leg and back strength. Hence, smaller lifters, having not maxed out their grip yet, lift more in the deadlift (since you have a slight mechanical advantage there) and larger lifters can handle greater loads with their legs than their hands can withstand.
Looking at records, I think the greatest deadlift these days is around 925 and the greatest squat is around 1050, give or take. The grip limiting factor would explain why in WSM and other venues where straps are allowed the deadlift jumps up to around 1050 or more again.
If this is the case I wonder if there is a big push in the powerlifting circles to allow straps so weight will continue to increase.
Any comments on this?