Different people use different terminology so I'm not sure which parts he's referring to, but when that part is used on a truck, it holds the lower ball joint in place from moving forward during acceleration and rearward during braking. The position of those ball joints, and the position of the wheels, is critical for proper alignment. That affects handling, pulling to one side, and tire wear. If they are simply bent a little, it might be possible to readjust the alignment to overcome that, ... On cars and trucks that provide adjustments. Yours does not, so to put the alignment back into specifications, bent parts must be replaced.