That sounds really interesting, and yes, I do come across people who find themselves detached from it.

The site that you linked is down at the moment, but I'll just offer some view points on it.
I think 1. is true, in that how some people can do somethings online to hurt others, while usually with their characters, they cannot possibly react in the same way as well. It is probably due to them not seeing the person behind the written text?

And for 2. It may be a reality, if the community itself is very clique-ish. Like they ward themselves up against outsiders and people who want to join the community may find themselves octracised against. Or it may be because of their characters. Alot of teens who spend their time online, have a problem with self-confidence, and in real life, they find it hard to fit in or to talk to a group of people. It will not be surprising if that same lack of confidence translate online, leading them to feel detached.