Throughout most of history, design was a process applied to physical objects. Raymond Loewy designed trains. Frank Lloyd Wright designed houses. Charles Eames designed furniture. Coco Chanel designed haute couture. Paul Rand designed logos. David Kelley designed products, including (most famously) the mouse for the Apple computer.
Design thinking is trotted out as a salve for businesses who need help with innovation. The idea is that the left-brained, MBA-trained, spreadsheet-driven crowd has squeezed all the value they can out of their methods. To fix things, all you need to do is apply some right-brained turtleneck-wearing “creatives,” “ideating” tons of concepts and creating new opportunities for value out of whole cloth.