I hope you are aware that the positive effect you describe also has a negative side. Those people who refuse to join Facebook (for good reasons as we were taught) are getting isolated. So who can tell what the net result is?
This is such a stupid argument. If 5 people do something that the 6th person doesn't want to ..doesn't mean the onus is on the 5 to stop doing it.
Surely that depends what the thing is?
Facebook is not that thing for sure. There is someone comparing it to Tobacco in some other comment. HN really is too much sometimes and often in its own bubble. The same arguments can be made against the Internet as a whole.
So just hope you will never be the one against the five when five people want to give you a beating...
Yes exaggerate the claim to be completely different from the real situation. If you think Facebook has it's demerits then be consistent and say the same about all of the Internet. Because your Grandparents aren't on HN, HN should be banned as well.