Late but I’m pretty sure it’s a byproduct of the RHLF process used to train these types of models. Basically, they have a bunch of humans look at multiple outputs from the LLM and rate the best ones, and it turns out people find lists easier to understand than other styles (alternatively, the poor souls slaving away in the AI mines rating responses all day find it faster to understand a list than a paragraph through the blurry lens of mental fatigue)