For one thing: bullying isn't a "normal healthy part of growing up" It's not normal to get bullied, it's not normal to be a bully. It's not something that ought to be common, it's preventable, avoidable nearly always.
And there is no value, nothing learned in kids bullying each other. It's just a failure to teach and support mutual respect.
But when many people feel like they could be ostracized, rejected from the tribe, unpersoned over any random little thing that failure is massive. 4/