not to be too pedantic......aw hell, yes I am, but here goes anyway...

To extend the principle into even greater use and meaning----one point of the CAGED system is that every chord is derivative of those 5 chord shapes. In some cases one must barre, but in many cases thes "moveble chords" become another voicing or inversion as an open string naturally substitutes for one that might have been stopped in another position on the neck.

It's also a valuable tool for learning the interrelatedness of chords-----the almost endless ways to vary I IV V.