What we're talking about here is the community's sense of basic good conduct: for example, that it's bad to be personally aggressive to other users. On this, fortunately, we're not nearly so divided.
I don't think "groupthink" is the right word for that, because there are few views, if any, that cannot be expressed in a substantive and civil way. Minority opinion, reasonably and politely expressed, doesn't do too badly here. Some negatively scored comments do fall into this category—not much more than 1-2%, if that many. That's something we care about and watch for, and may try to do something systematic about, though in practice it's usually enough for a few fair-minded users to upvote those comments back to par.
Far more common is that people post comments which aren't substantive and civil, and then, upon getting downvoted, complain that groupthink is suppressing them.
In general, disagreeing is just fine; one can do so in a polite way. Being a 'jerk' usually entails disagreeing and being vitriolic about it. (An example of this is insulting the person rather than addressing why one disagrees with the arguments in the comment itself.)
Is that desirable? A better debate surely entails more than one opinion. I also don't know what a 'jerk' is, someone that disagrees with the group think?
I just don't think its that big a problem. But thats just one opinion that might differ from the collective and therefore must have no merit? An odd place. Over engineering! To be expected I suppose.