I’m fascinated by this phenomenon. Just a year or two ago here on SurviveFrance good discussion (thought out and evidenced arguments, from different points of view) was welcome, I think by pretty much everybody. But more recently the very different approach articulated above has emerged: the wish for merely an echo-chamber for their own views; a wish, explicitly not to engage in discussion.
EDIT:
Amazing! Just also looked into the ‘Eurovision’ thread and found almost exactly the same thing: