Trauma to me means there are ways of responding to painful experiences that can keep you in that painful state for a very long time, and/or make things worse. I recognize that simple fact from my own experiences. In that lens, its helpful to reflect on your responses to painful experiences to stop them from developing into long term traumas. Maybe that's why this book, or at least the title, seems to resonate with people. (I haven't read it)
...But it's also good to know the author of the book was wildly mis-citing things