I think your comment, while not especially constructively formed, is a good warning about alarm-ism. However, I think you should at least consider a few things:
1. The concerns about D&D were quite different. Most parents admired the creativity involved in role-playing. The concerns came from a relatively small subset of parents who were concerned about the morality of the subject matter (monsters, demons etc.). For the record, I thought at the time that these concerns were pretty silly and had little merit, and still do.
2. Just because there have been moral/social panics in the past, doesn't mean the concerns about social media today are invalid. Sometimes worries are wrong, sometimes they are right. Having been wrong before does not make it rational to never be concerned again.
3. It is entirely possible that concerns about high-volume TV watching were correct. Just because my generation (X) survived the TV era does not mean we came out of it unscathed. Much of the ignorance and obnoxiousness of our current age may very well be caused by today's middle aged people growing up watching television. (Or maybe it was the lead paint our parents grew up with?)