In the Y2K era of ubiquitous Proactiv commercials, skin care routines served the apparent purpose of treating unwanted acne. But in a TikTok-powered world where consumer allegiance is fueled more by lighthearted show-and-tell than bona fide product utility, 9-year-olds are drenching their faces in anti-aging serum before displaying a single sign of puberty. Now, a...