There are some similarities with the emergence of the more kid-friendly Transworld magazine in the 80s (which was founded as a response to Thrasher's semi-pornographic Indy ad with an underaged girl). On the other hand, staffers GSD, Blender, Mountain, JGB, and Dave Carson gave TWS enough credibility.
If these YouTube stars are disrupters, they must have done so unwittingly, at least initially. In more ways, their success is due to mainstream pros failing to see the potential in YouTube. It must also be fairly laborious.