This isn't true, or at least there's more nuance to it: I just logged in to my number-based account which I must have last used in 2002-ish while playing Ultim

This isn't true, or at least there's more nuance to it: I just logged in to my number-based account which I must have last used in 2002-ish while playing Ultima Online, as another commenter in this thread mentioned. My account still existed and all of my contacts were still there.