How accurate does this judgment seem to your own knowledge of Mount Stupid, and further, what tools other than having your gross ignorance exposed have led you downhill toward expertise and humility?

I mostly agree with your analysis above; I would add, however, one very internal factor. People who do not possess significant expertise in a complex area almost always tend to underestimate the complexity of all complex systems. Even if they read on complexity, they rarely get an intuitive feel for it. So, reading a few popular books doesn't just introduce the problems you have stated above. Since there is no intuitive understanding just how complicated things are, a person feels that the few information they have gleaned are sufficient to make an informed opinion on a topic. IMHO, this general problem also stands behind the popularity of many simplistic (and ultimately destructive) ideologies based on simplistic approaches to complex systems (such as, say, communism or libertarianism).

Along those lines, a thing that helped me a lot in this regard was becoming an expert in a complex field. Seeing how very intelligent people form deeply wrong opinions about things I understand made me very, very aware of similar biases in my thinking about other fields. It didn't cure me from forming such opinions, but it does force me to reexamine them aggressively as soon as I realize their existence within my mind.