Well, yes -
Groupthink is not unusual in any forum, and there clearly are people who get shot at just for not sharing the view of the cheerleaders in respective threads.
On the other hand - not everybody making negative remarks is providing critical analysis. I see it less often that people who provide a real analysis (i.e. providing as well sensible reasons for their view) get shut down. More often it is just a negative view unsupported by facts clashing with a positive view unsupported by facts ... and sure - this only can end in a shouting match, can't it?
Maybe we should all try to provide more supporting facts when we state controversial opinions ... this site certainly would gain from it.