The scale handles are hard to tell apart if you are scaling a small object or if you are not zoomed in enough. (Of course one could zoom in to find them.) I suggest that when they are really close to each other only the “main scaling handles” should be visible/selectable.
If all the corner boxes are gone one could work more quickly with scaling, not zooming in so much. The corner scaling handles could be visible once one is zoomed in close enough that it makes sense to select individual scale handles that one can tell apart.
So in the case shown I could select a side/center scale handle and reduce the width of that garage door without zooming in, and without risking that I also scale the depth of the object.
Yes, its possible to code only certain scales into dynamic components, I just find it would be quicker to model if selecting only “Middel of side” handles was easier also on other objects, when visibility makes then hard to tell apart.
Or maybe I just dont have enough dynamic components in my library 
But even if it was a dynamic component it would be useful. I could then select the component along with the raw geometry of the side wall and scale the whole thing together. If you select other things together with the dynamic component the scale handle filtering of the dynamic component will not work.
I´m just advocating here for a few clicks saved here and there, and scaling is done often on all kinds of geometry.
