These patterns are learned from magazine articles and other long-form publications. The tendency to have unnecessarily pithy/hooky section titles is one that particularly irks me, but it's not like AI invented that. I was reading some DIY books that are published by a company that does a lot of web/magazine work and they structure the text in the same way (this is all pre-LLM).

Content creators are starting to include these traits into their scripts now, too. It's uncanny when you (literally) hear it.