According to wikipedia, the initial release was 20 July 2001. By 2001, we had been using mpeg type audio for some time, whatever audio Cinepak pushed, RealAudio, etc. Hell even AAC came out in late 90s, but didn't take off for much much longer. FLAC was a baby while other formats were wearing long beards and suspenders. Only audiophiles used it, and it really didn't take of until AFLAC and iTunes/iPods.