In a nutshell I think what he is ask about is the ability to take a model you have built, for example a bookshelf, and grab the right side and move it to the right an additional 3" and it automatically extend the horizontal members (shelves, top, bottom etc) without having to manually scale/push/pull each item to match the new side position. I think this is a common request and not one I recall having found an exact answer to myself. It is frustrating because it is a fairly common feature found in many cad/3D rendering software. Another common complaint is taking an object (say a rectangle) and be able to click on it and resize it exactly by entering in the dimensions (IE X,Y,Z) you desire. It's not that SketchUp can't accomplish this task, it's just way more complicated than it should be, especially compared to similar software.
To be yourself in a world that is constantly trying to make you something else is the greatest accomplishment.
~Ralph Waldo Emerson