Well, shocks can also keep the wheels touching the ground more often on bumpy terrain, for better traction. Think climbing a hill on rooty, rocky singletrack, without losing traction and therefore momentum.
But yeah, no: In order to get to the point where you actually need suspension to stop the frame snapping in half or something like that, you've gotta be doing some real X-Games shit. And at that point you need full suspension anyway, not just a hardtail.
(Either that, or your frame was defective and unsafe to begin with.)