I think that is part of it for sure... a fair number of the people presenting the objectionable christian atheist attitudes (that were being rightfully criticized by the OP) ARE North American or British white people who have been influenced by people like Richard Dawkins and Christopher Hitchens.
I know little about Hitchens, but with regards Dawkins I do wonder to what extent people have taken away messages he didn't intend. Like, a lot of atheists who quote Dawkins seem really belligerent toward Christianity, whereas he himself has said he likes Christian music/hymns.
Oh agreed. It's like a lot of things, "it's not the band I hate, just their fans". Dawkins has gone off the edge into belligerence since, but less about atheist dogma and more about other grumpy old white man stuff.