I've been involved in the parkour scene for over a decade. This entire debate sounds very familiar. It is the debate you get within any group of people that follow a passion. You get one group that is totally purist and wants to retain the essence of what brought them to the activity in the first place. And then you've got all the newcomers that join in because it's popular (with only a small minority of them taking on the purists attitude). It's almost impossible to reconcile these two, essentially opposing viewpoints.
Stunting on youtube will come and go, just like any trend. After it loses popularity the purists will be the only ones left doing it.
Kwebellkop is a symptom of how poorly run youtube is- it's not about content or even it's quality any more. It's about marketing to children and the ad revenue that yields. No other medium allows for such unregulated advertising exposure to children. It's big money. The new gold rush.