I think you may be taking "off the ground" too literally. If your leveling system were not permitted to raise any tires off the ground, the amount of leveling ability provided would be too small to be worth the trouble. I take it to mean that the levelers should not be used to take ALL tires off the ground, as in trying to use them to raise the vehicle to do maintenance. In fact, with my Windsport, when auto-leveling does lift the front tires off the ground, it will automatically keep the rear jacks from extending so the rear tires stay on the ground.
I use chocks under the tires that are still planted on the ground, by the way, for extra safety.
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