For everyone else who felt similarly, the explanation is in the previous post (linked near the top of the intro). I also found this confusing because the whole intro felt like it was building up to define the concept and explain why it’s a (the) problem. I even googled the term, thinking it may be some term of art I’m just not familiar with. Then I looked back at the intro again, and inferred that it must be pointing back into the post series… just conveying that poorly.