I'm old enough to have gone through this about the internet and literate enough to have read about every other time this happened back to the invention of writing which was meant to turn us all into imbeciles according to Socrates.
A lot of the "this has happened since the dawn of time" falls apart when you remember we have created in the past 30 years technologies that have never existed and are changing the nature of civilization.
Your example is spurious. Writing had existed for 2 thousand years when it reached archaic Greece. It had existed in Mycenean Greece almost a thousand years before and been forgotten. A Greek decrying "youth these days rely too much on writing" was already an empty worry from the experience of almost 100 generations.
Touchscreens, smartphones and the Internet are a few decades old at most and no one knows the long term impact of them on civilization or the youth. Pretending it's the same is bad reasoning.
> As middle-aged folk identify the problems with the social networks they grew up with, youngsters may already be moving on.
One of my proudest parenting moments was discovering that a child had independently realised that their online presences ought to be multiple and not trivially correlated.
A better, prouder moment, for all involved, would be not that the child arrived at this marvelous conclusion "independently", for that outcome (by your admission) is quite rare. Else, it would not be remarkable enough for you to comment.
Instead, we want to arm our children with the tools so that they arrive at that same conclusion repeatedly and predictably. Better yet, we would all do better if we simply eliminate such harmful algorithms and creepy practices entirely.
Leave the kids alone. They will figure it out.