I can definitively say llms.txt is not used by any AI players. I run a blogging platform with around 80k blogs and /llms.txt is not requested by anything (other than humans checking to see if there's an llms.txt path).

All regular pages are aggressively scraped to the extent it's a problem I have to consistently manage, but not llms.txt.

No, requesting "Accept: text/markdown" in the headers and returning markdown is the more agreed upon standard at this point.[0]

[0] - https://acceptmarkdown.com/

yes, they do.

anyone who's, even slightly, clued into how agents access documentation, has been making changes to their pages. ex: https://searchtxt-web.fly.dev/search?q=aws