The myth? That designers possess some mystical, creative thought process that places them above all others in their skills at creative, groundbreaking thought. This myth is nonsense...The phrasing "above all others" is a strawman - it is obvious that this cannot be true. Creatives in general do have attributes that will, on average, have them produce more creative results than somebody who is not a creative. One way of looking at this is by using Bloom's Taxonomy. Creative people just spend more time at the higher levels of Bloom's, so are just more experienced in those modes of thought.
...we have had breakthrough ideas and creative thinking throughout recorded history, long before designers entered the scene. When we examine the process in detail, what is being labeled as "design thinking" is what creative people in all disciplines have always done.The big difference in design thinking versus other creative modes of thought is the design process. The exploration of a solution space that following a systematic approach to design allows is going to be more thorough and produce higher quality results than a creative stab. It is the iteration of cycles of Analysis, Synthesis and Evaluation that make the process more than traditional creative thinking. There's a good book on the topic: "How Designers Think: The Design Process Demystified" by Bryan Lawson.
Traditional creative thinking values originality whereas design thinking favours appropriateness. The originality versus appropriateness thing is a bit more yin-yang in its relationship than polar binary opposites but the focus of design thinking is very much in appropriateness.
Yes, I have a search theory model for how design thinking works -design thinking, as encapsulated by the design process, that is basically a human form of a genetic algorithm.