I haven't run into it because it previously has been made known only to (some of) those who ran into a validation problem.

No, I think that's incorrect. I have never had an authentication problem on either of my computers here, yet when I visited Microsoft online last year to check on updates I ended up going through the authentication process. It may have been voluntary at the time, but as I recall it was actually necessary if I wanted to set up the computers to receive automatic updates.

SRS