Ouch, those factory ARRMA pinions don't stand a chance of 6S power. Its crazy how quickly they fail. It may sound repetitive, but on nitro RC 1/8 I have never stripped a clutch bell pinion like that, and they are the same teeth, 14T / 15T. ONLY one time and it was HSP china brand, learned my lesson. I am willing to bet a lot of those pinions are low grade cheap metal.
IMO the happy medium of acceptable bashing tear and wear is on a 4S, and pushing it on a 5S. Once 6S becomes the norm, they wear out quick. (... imo) it is not a fact ///