I have a problem with belted cartridges, but not with the original ones, like the .300 and 375 H&H, nor the straight cased ones, like the .458 Winchester Magnum and the .458 Lott. The H&H cases don't have enough shoulder to headspace reliably, and the straight cases have no shoulder at all, and must use the belt (which is really a modified rim) for that purpose.

The problem arises with cases like the .264 WM, the .338 WM, the 7mm RM and other similar cases, which have a perfectly good shoulder to headspace on. With the cartridge in effect headspacing on both the belt and the shoulder, unless you are super careful in your loading technique, the case starts to stretch just above the solid head, which will eventually result in case separation. For the average hunter this is not a problem, but for the long range target shooter, who may go through hundreds of reloads in a season, and who doesn't need a case separation in the middle of a match, it is a different story. I used to shoot a 7mm RM at 1000 yards, and I found the belt a nuisance, since I had to be careful not to set back the shoulder in the resizing operation. Eventually I started using a neck sizing die and full length resized only once every four or five reloadings.

For a cartridge with enough shoulder to effectively headspace, the belt is only an affectation. However, it did sell: witness the demise of the .284 Winchester, a cartridge identical to the .375 H&H at the head, but without a belt. The fact that it even exists at all today is due to the success of its wildcat offspring, the 6.5X.284.