I was also a teen at the time but I knew about their idolization of Hitler pretty soon after it happened. I do remember it being mentioned in the news, but their Nazism was always just a quick side note, only remarked on in passing before focusing on the fact that they played Doom and listened to Marilyn Manson, which was where all The Discourse got centered. Their fascist inclinations were what got written off as typical edgy teenager behavior whereas the shit that really was just typical edgy teenager behavior (at worst) was what got all the attention. A decent example of emphasis/de-emphasis as a tool of propaganda in news media.