In fairness to Dusty, the two of them didn't actually pitch a ton of innings. The most starts either had in a season was 33 and they only went 213, 211 and 211 IP when the league leaders are routinely in the 230-260 range.
I don't think there is really blame to put around at all. Pitching a baseball is a very unnatural thing to do. Some pitchers like Glavine, Maddux, Clemens, etc are just born with rubber arms. Both these guys throw hard, and game after game it builds on you. They're just too fragile. Shit happens.
IMO, I also think they don't pitch enough growing up. Guys get on pitch counts early and in the minors hit 110 pitches and are done. They don't ever get used to throwing 130 or so pitches. Their arms aren't conditioned for throwing a lot and throwing often like they used to be.