He's not denying that it has. He's refuting his former naive belief that open communication would be some kind of magical pixie dust that would make better everything it touched.

I can relate to this. I remember thinking, back in the 90s, "once people can directly talk to people from other cultures, and see each other's common humanity, how will there ever be any more war?"

Turns out that was an extremely naive belief. Just the opposite is true in many cases: direct communication can aggravate differences. People's self-righteousness tends to escalate when they are directly exposed to their ideological foes.