The case, in which closing arguments were made on Thursday, is the first of many lawsuits brought by thousands of young people, school districts and state attorneys general against companies like Meta, Google, Snap and TikTok. The plaintiffs in these cases do not accuse the companies merely of serving up bad content to young people; they argue that the very design of social media is intentionally engineered to create compulsions and habits of overuse, regardless of the content provided.