Cushions much like the ones on your couch right now are designed to take the impact force that comes from the piston moving quickly and abruptly stop when coming in contact with the Head or Cap. While this can happen occasionally without major damage to the cylinder, over time this impact loading can cause the tie rods to fail due to fatigue loading, or can cause excess compression loading to the piston, head or cap. This causes distortion of these parts which will ultimately lead to cylinder failure.
