In those pages, Bobby discusses how "game improvement" club designs can hinder players from developing a more dynamic swing.
Baggers Summary -
The premise is that a lower/rearward clubhead center of gravity plus clubface offset help produce higher shots but due to the nature of their design, conditions players from learning how to hit down enough. As a result someone conditioned to using game improvement clubs have difficulty when moving to blades. Hence the general consensus that blades are reserved for better players.
In reality, blades (or blade-like designs) are the best game improvement club because they don't reinforce compensations.