I think it's also only recently that the interactive part has been big at all. Not entirely sure, but it feels like 2007 or 2008 was the first year it was one of those big all-the-cool-kids-in-SF-must-fly-to-Austin deals. Certainly the late-90s SXSWs didn't have anyone flying there for the tech content (though plenty were flying there for the music and films).