That timeline of the war on fun represents very poor logic. You can't argue that someone is wrong about the potential dangers of technology just because someone else was wrong about an earlier technology. This kind of logic would have it that smoking cannot possibly be harmful to health, because in the past people were wrong about health effects of other habits, such as chewing gum, winter hiking, etc).
Carr's arguments about neuroplasticity might lack rigorous scientific backing, but there is plenty of evidence that the pervasive distractions of modern tech can be harmful, and that kids need more help these days to develop the skills to manage distractibility. Similarly, while there's no evidence that being online is any more likely to expose kids to sexual predators than hanging out in the streets, that doesn't mean that the de-individuating effects of online interaction aren't real.
The techno-optimists are wrong about the benefits of technology just as often as the techno-pessimists are. Meanwhile the rest of us have to figure out how to navigate a world in which every new technology brings both benefits and problems, often in equal measure.