This is true (to an extent) for SS buckles on nylon webbing; over time you'll wear out the weight belt where the buckle "pinches" it.... that is the tradeoff for having a stronger and more secure buckle (vs a plastic buckle).
The rubber freediving weight belts like the Mako and IST belts being discussed do not use the same type of buckle used on a traditional nylon webbing weight belt. Very little "strain" is put on the rubber by the buckle itself, about the same as traditional belt buckle on a leather belt holding up your pants... the reason is that the rubber has a lot of "friction" against the exposure suit, and the weights can ride lower and are supported by the pelvis when walking on land (again, see the video on the Mako website), and near-zero strain on the buckle when horizontal in the water... the belt does not need to be cinched down super tight.
After using traditional nylon webbing weight belts since 1976, I am a recent and happy "convert" to rubber freediving belts.
Best wishes.