FWIW I've basically had the conversation seen in the show, albeit with a friend, not a stranger. He was running XFCE because it was the default in Debian, and I

FWIW I've basically had the conversation seen in the show, albeit with a friend, not a stranger. He was running XFCE because it was the default in Debian, and I was running KDE (have been for twelve years). So I found the exchange at least plausible. I think it boils down to the fact that, some people find DE quite uninteresting (unlike editors), while others have strong feelings about them.