This has to be one of the clearest articulations of Design Thinking I've come across in a while. In the course of talking about moving beyond Design Thinking to something the authors call "intervention", they do an excellent job of embedding an explanation in the context of how it should be used and built upon.
The principles of this approach are clear and consistent. Intervention is a multistep process—consisting of many small steps, not a few big ones. Along the entire journey interactions with the users of a complex artifact are essential to weeding out bad designs and building confidence in the success of good ones.