I will take issue with coil springs.

Sway bars do not wear out like springs. Suspension coil prings are under continuous load and with time they take a set. This compression set results in vehicle sag, and usually means the coil springs need to be replaced, or spacers need to be added to take up the lost compressed height. Though the coil springs may sag, the spring constant will remain the same.

Sway bars, on the other hand, are under neutral load and will continue to function as designed, and with time they will have no noticeable loss in performance. There is no "set" associated with a sway bar.