I think this is where the issue comes from, I've had poly LCA bushings on my Duster for years with no issues BUT I made sure to install greasable pivot pins at the same time; IIRC the diameter of those pins is the same as the stock pivot pins with the inner sleeve installed. If you have to use a sleeve from an old rubber bushing on the pivot shafts to make it a tight fit (with no grease supply) in the poly bushings then yeah, they're gonna get destroyed. So if you're sticking with factory pivots, use rubber... if you want to use poly, you need aftermarket greasable pivot pins.
The poly bushings need a smooth lubed surface to rotate around, they aren't designed to flex and rotate with the LCA as it moves like the factory rubber bushings are.