With social media, we are talking about kids doing the bare minimum on homework in order to get back on social media faster. We are talking about large swaths of the population preferring to be entertained by social media then to engage in activities that would promote their success. We are talking about the same symptoms as addiction manifesting in kids because they are exposed to too much social media.

Your litmus test for generational effect is also flawed. Let's assume an inverse test as a mental exercise, where we introduce social media to a young population previously unexposed. Kids who are able to reject the pull of social media will replace the ones who cannot, the numbers will shuffle. After such a test is concluded, you will tell yourself you're right because on a macro-economic scale everything looks the same, but to an individual prone to social media overuse, his or her life will be different (likely worse).

That said, the issues you bring up are more important, and no one seems willing to tackle them. Perhaps a middle ground here is that the problems you listed are masking the problem of social media overuse, but that social media overuse is still a problem. It is not an innocent messenger.