Earlier quoted context omitted.
You're looking at it in isolation because you are not privy to the kids' social circle. What the gp is describing is a social cost imposed on the non-participant kid. If repeated often, this will lower their status within their social circle and (much like chickens) the least popular kids become the default target for emotional abuse and bullying. If they withdraw form their social circle to cut their losses, then th…
I get what you're saying but we shouldn't escalate this into a type of prison gang situation, there's significant middle ground. When the research is becoming clear that these dynamics and these years of a teen life cause so much harm, we can't be so fatalistic to say that giving in is mandatory.
Now combine the natural fact of cliques and fissures in small groups with the amplification/reinforcement effects that social media provides, and you can see the potential for acceleration/intensification of social stresses during formative years - like Mean Girls but potentially spread across the entire internet, or at least similar cohorts.