It was teenagers born in the mid-to-late 90s who first started displaying this trend so I think you're right that most parents of children today will have either spent all or the majority of their own childhood away free from that combination of smartphones and social media and are possibly more resilient as a result. Jonathan Haidt has also made the point that a lot of millennial parents grew up during a sort of "techno-optimism" era where people genuinely believed that the internet and this new technology was the greatest thing ever for human learning and communication and would bring us all closer together. There hasn't really been any sort of collective pushback against that idea by our institutions until very recently so I think it's understandable that there is sort of a delay in that message filtering back through society to parents.

I was just watching a TV series last night with a typical scene in which a mother was struggling to have a conversation with her teenage daughter because the child was essentially addicted to the social media on her phone. It was played for laughs, and it sort of dawned on me that basically every single depiction of this interaction in media is in a harmless "kids will be kids" sort of way. Like parents are frustrated by it but at the same time it's sort of just assumed that there are no deeper long-term repercussions and that it's just a different manifestation of typical teenager behaviour all generations exhibit. I think that perception is going to be quite hard to change and it probably explains why we've been so slow as a society to wake up to the possible risks despite warning signs that seem increasingly obvious as our hindsight grows.