User blog comment:VonGlusenburg/Alternate universes, probability and alternative outcomes/@comment-1310192-20120817010738

ASB originated in the scope of internet alternate history as a criticism, stating it'd be more plausible for alien space bats to allow a certain Nazi victory timeline in alternatehistory.com than it'd be for regular humans to do it. So it's nothing that makes it impossible; it's just something really implausible.