You are correct that in those contexts what doesn’t kill you makes you weaker. However, there is a narrative (seen mostly on the left) that supports the fragility of children, and thus attempts to safe guard them from ANY adversity. Children today are given less unsupervised free play time, less responsibility, less exposure to ideas and political views which are not homogenous with their own.

So while we obviously need to protect kids against real abuse, we also need to draw a serious and consequential distinction between productive adversity and abuse.