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