When your steering is bound up in rocks, the steering force can overcome the spring pressure and then put ujoint in a bind bc of the upper spring compressing. This allows the lower kingpin to move vertically in the lower bearing.
It then puts a ton of force onto the axle shafts, u joint, spindle and those tiny spindle to shaft bearings.
Springless avoids this. But the plastic instead can wear, the ultimate is the ECGS Bronze/brass upper kingpin inserts with grease and setting/checking the preload.