Shed Dog is right, you can't replace experience, I think that's all he's trying to say. It's got nothing to do with age, it's just that usually if you have lots of experience you tend to be older. And you can't replace experience with university degrees or enthusiasm as much as these things are good and will contribute to eventually making a fine pilot.
It's only when the proverbial hits the fan that a lack of experience usually becomes a player, hence managers et al think they can get away with reducing experience levels for short term financial gain.