I'll let a metallurgist answer the why. I just know they do.
Compared to a button rifled barrel, it seems like you get about 2/3 more life with cut rifling and a little more with hammer forging. Add chrome lining and it doubles the life. Nitriding? The jury is still out on that, but from the limited reports I've heard it's about triple the life of a plain button barrel depending upon if you started out with a buttoned, cut or HF barrel and if it was stainless or carbon steel with the edge going to carbon.
Keep in mind, if you can afford to burn out a barrel, you can afford to replace it.
I agree with that, but it depends upon how much you shoot and how often you want the disruption of swapping barrels. I shoot mostly button barrels and just plan on getting a new barrel every year.
Keep in mind that "worn out" is relative to your expectations and a chrome-lined barrel may not even meet you initial expectations.
