Those are all very good points, thank you. I strongly agree with all of that, with the exception of:

The usual tactics should work: "I know it's weird but I have an online friend who's definitely signing up, and when we discussed his/her motivations they seemed actually quite reasonable, I'm thinking about it a lot".

I don't know how effective this really is, but I'm skeptical of this approach because "I read it on the Internet" is generally not a good arguing tactic.