The thread is discussing the value of this type of conceptual presentation to a design portfolio. 'Conceptual designer' by your definition would basically mean 3D visual artist. That's not quite 'design' as it's being discussed here, though I wouldn't call it academic or instructional either. For design work, the final product rarely demonstrates the skills needed to be a good designer in real business settings. Hiring managers want to see the process that led to the final product.