Another reason people might flag it is in the same vein as the one the gp noted, in that there's little to engage with. Given how other threads have gone on similar issues, they've generated a lot of heat and unfortunately very little light. Rather than create another thread where this can happen, raising tensions even higher, they're flagging it to prevent the same thing happening again, even if they support the post.
However, someone just flagging it so others can no longer comment on it isn't very productive. That is what bothers me about it.
I can totally see your point of view on this particular story.