While the "freehand vs. guided" debate is, in some respects, rather meaningless, since a lot of it relies on the skill of the sharpener, I think you might have inadvertently hit on
one benefit of guided systems.... that is, it can be good "training wheels" to learn to sharpen. It allows the sharpener to learn the various aspects of sharpening while eliminating the one factor that can be the most difficult to learn... holding a consistent angle. It can also be of benefit if a sharpener wants to transition to freehand in that it gives them a nice bevel to work off of, (and a way to reset it if it gets totally messed up).
Not disagreeing with you, but I think both have their place, and if you enjoy sharpening, both methods can be fun to play around with... and is a great way to continue learning IMO.