Everyone reported it at the time but here's one story that I found:
https://9to5mac.com/2018/02/03/ios-11-3-icloud-sign-on-solution/
There is no better time than now for Apple to launch this. The problem with Facebook isn't that they can see what you post, it's that they follow you all over the entire web because of the ubiquity of Facebook's sign in button.
I want to have Apple sign me in to websites without a password. Work with a token so that that website will always log me in on any iPhone, iPad or Mac that's logged into my Apple ID. Secure it with Face ID or Touch ID. No passwords. No Facebook.