MS began using [MP3] in 1998. The FSF says “they would have been safe” [using Vorbis in 2000]. That overlooks the inconvenient fact that [Vorbis 1.0] was not released until July 2002. It’s hard to imagine how MS could have chosen the “safe” open-source option when it didn’t exist yet.
Ed Bott on the FSF’s campaign for Ogg (my edits for brevity)