Not trying to speak for any of the contributors, but I think it's a key sign of a professional when your training theories evolve as you gain more experience, new science is discovered, and when you simply gain the benefit of hindsight.
For example, I think Cressey and Robertson have mentioned that there are some movements in Magnificent Mobility that they no longer advocate as much. Berardi has shifted away from the P/F, P/C designations. Thibaudeau has gravitated away from a general carb cycling plan.
Cosgrove makes it a regular habit of telling people he doesn't apologize at all if something he says today contradicts something he said years ago.
I think new readers/new trainees should read whatever they can. There's (almost) no such thing as a "bad program", and if it appeared on T-Nation, then there's definitely nothing wrong with someone trying it out as long as it's appropriate for their goals and training level.
Just because a coach may have changed their stance on a topic, doesn't mean it was crap to begin with. They wouldn't have advocated it in the first place if it was worthless. It's just that, as time goes on, they find an even better way to get things done.