I think having the concept of PCAs prevents some mistakes in reasoning on an intuitive day to day level of reasoning. It nudges me towards fox thinking instead of hedgehog thinking. Normal folk intuition grasps at the most cognitively available and obvious variable to explain causes, and then our System 1 acts as if that variable explains most if not all the variance. Looking at PCAs many times (and being surprised by them) makes me less likely to jump to conclusions about the causal structure of clusters of related events. So maybe I could characterize it as giving a System 1 intuition for not making the post hoc ergo propter hoc fallacy.

Maybe part of the problem Jonah is running in to explaining it is that having done many many example problems with System 2 loaded it into his System 1, and the System 1 knowledge is what he really wants to communicate?