I think you’re missing the reality that white supremacist views weren’t necessarily missing from 4chan before Stormfront came. Habbo Hotel may have been mostly people trolling, but there was an undoubtedly racist subtext to 4chan for a long time. For some people it was probably ironic, but the downside of anonymity is that it’s difficult to differentiate between ironic racism and genuine racism so 4chan served as a safe harbor for racist, misogynistic teens before things like /pol/ had a semi-coherent ideology. Just because someone is young and has been raised in a prevalent culture of tolerance doesn’t mean the worst culture baggage hasn’t been passed on to them. The reality is that a lot of the racist true believers are young, just look at Stephen Miller in the White House. He doesn’t have the excuse of hanging on to the cultural baggage of his youth and neither do many of the true believers that populate boards like /pol/.