User blog comment:Brandon Rhea/How we're testing the fandom.com domain migration/@comment-67.2.0.226-20181025023728/@comment-73.223.156.227-20181026140301

That's the point of testing a small number of communities first. I don't know what experience you had but they obviously didn't test anything first or they didn't care. I don't think FANDOM is going to risk all their income by making this fail because people can't login, comment or edit.