If you think about, and I know it to be true from almost 25 years of working with kids, people who heavily engage in using these games develop very, very poor social skills since they are never dealing with humans. Human contact means little to them and while they may not turn out to be mass murderers, they tend be socially immature and uncaring of others.
I am going to agree. But (you knew that word was coming) I think you might have cause and effect the wrong way around. Do they fail to develop social skills because they play games? Or do they play games as a way to avoid people?
We could both argue each side of the debate equally well, methinks, being reasonable and educated people.
I was a very shy child. Hated to talk to people, so much so that my two forays into public speaking at school ended up with me throwing up in front of the class. If we had had computer games then, I'd have probably hidden in them. Instead, I hid in books, but also had to deal with people. Never liked it much, but it was practice.