Any gun will aquire holster wear if it's holstered and carried. And if you're going to carry a gun, you need to practice with it. And dry-fire with it. A lot. It's a life-saving tool, it's gonna develop holster wear.
Leather can, will, and does hold on to grit and grime that makes its way into the holster.
Kydex is generally able to keep things much cleaner - you can literally hose it out.