When done poorly, it means you get trapped in a room with some folks with religious zeal and a set of post-it notes in various colors, sharpies, and colored paper sticky dots for a few days. Afterward, you get... not much. It's just like agile.... if the "practitioner" is hyper-focused on the rituals and ceremony, it's easy to miss doing actual work.
My personal beef with the concept is that the ceremonial aspects mean you need a special UX/design/etc specialist, who comes in and leaves. Usually the "design" processes focus on 80% solutions, and nobody comes back to finish the other 20%. You used to notice this when people built out responsive websites -- key functions that weren't in the "Top X", would just disappear on mobile.
Then when I started leading the design thinking sessions all I can think of is how silly all this is. When we went remote during covid, introducing in virtual whiteboards like Miro and Figma, made the rituals and ceremonies more tolerable and more importantly actionable.
After all this time weaving through Stanford where this all went down, the corporate war rooms all over, settling down now, ultimately I think it just comes down to this: design thinking is really just empathetically solving problems rather than apathetically solving problems (as in working off requirement documents or best practices or protocols or just because you're told what to do).
All the little ceremonies and rituals is inclusivity of everyone to empathize and feel good about each other, and consider things from additional POVs. Which back then at the tail end of Gen-Y transition into the workforce was needed. Now you talk to the Gen-Z workforce about using empathy at work more and they'll just go: facts.
For instance, you need a floor plate of the second floor of a building to be a bit bigger to accommodate a certain type of room. So you make the second floor cantilever over the entrance, thereby also providing the functionality of an awning that protects people from rain while they wait for the bus. This is a bit of a silly example because the cantilever adds cost etc but that’s the general idea. Identifying opportunities that are “win-win,” might be a crude way to say it.
In my experience this is a particular mode of thinking that some people are clearly better at, and those people tend to be the superstar designers. Whether it can be taught or not is a bit of an open question.
Any other definition I’ve heard for “design thinking” doesn’t really make sense to me, but that might just reflect my background.