Professionally typeset books. Designers have been typing it—and the other dashes—manually using modifiers+hyphen on Mac since 1984. You can type them—plus the bullet character—today on iOS by doing a long press on the hyphen key.

I think it comes from the RLHF. If you haven't interacted with LLMs enough to get turned off by it, I think that kind of speech is seen as powerful and confident.

I wonder this too. Is there so much of this style, or does it indicate some aspect of the LLMs’ sensemaking?