Not touching that thread with a 10ft pole, but Reddit is mostly Americans, even /r/Soccer. And switching allegiances to teams is something we do to a greater degree, as it's a totally different sports culture. Which is not a justification/excuse at all. It's something I disagree with and can't defend. Of course there are diehard american fans, but we definitely have the larger propensity for changing support, or at least find it easier. And there's where the clash of heads comes from.
None of this is new to anyone here of course. I just see how/why it could have turned into an allmighty shitfest.
edit: didn't even see that's /r/reddevils. ahahaha.