It's not just analytics. ChatGPT saves all of your conversation history - I don't know if they save the full conversation text in postgres, but I'd assume they at least save conversation metadata there.

You may not want this from a privacy perspective, but as a user I find it to be a very useful feature, e.g. I can see my full history, I can easily share conversations with a share link (and it's the exact version of that conversation, not like a URL where contents can change).