This site and many others were littered with OpenAI stories calling it the next Bell Labs or Xerox PARC and other such nonsense going back to 2016.
And GPT stories kicked into high gear all over the web and TV in 2019 in the lead-up to GPT-2 when OpenAI was telling the world it was too dangerous to release.
Certainly by 2021 and early 2022, LLM AI was being reported on all over the place.
>For most of the world LLM's did not exist before those dates.
Just because people don't use something doesn't mean they don't know about it. Plenty of people were hearing about the existential threat of (LLM) AI long before ChatGPT. Fox News and CNN had stories on GPT-2 years before ChatGPT was even a thing. Exposure doesn't get much more mainstream than that.