Here's a file showing that method in action.
Notice how after the displacement is reversed, any new vertices created during the Voronoi fracture process that get back-transformed do not end up in the exact location they "should" be, because their position calculated during the Voronoi fracture and post-fracture subdivision is an interpolation of neighboring verts/edges, not the actual location they would be at if they existed pre-initial-displacement...so they're back transformed "further" than they should be. So...you get nice interior breakup, but a lot of surface artifacts, self-intersections, etc. These artifacts can be somewhat minimized with more initial mesh subdivisions.
Notice how after the displacement is reversed, any new vertices created during the Voronoi fracture process that get back-transformed do not end up in the exact location they "should" be, because their position calculated during the Voronoi fracture and post-fracture subdivision is an interpolation of neighboring verts/edges, not the actual location they would be at if they existed pre-initial-displacement...so they're back transformed "further" than they should be. So...you get nice interior breakup, but a lot of surface artifacts, self-intersections, etc. These artifacts can be somewhat minimized with more initial mesh subdivisions.