Philosophical Differences
The reason that Martial Apprentices did not gain much power from techniques of their creation or contribution that were highly individualistic versus techniques of another's was that their bodies were still shackled to human limits, barring their brain. Martial Apprentices also possessed nascent Martial Paths, thus even if a technique was highly synergetic with their Martial Art and body, it did not end up resulting in the kind of explosive power that the Void Pathfinder technique gave Rui by virtue of being synergetic.