Hypothesis to which I have given 30 seconds' thought: the problem with social media, is that the person who announces a provisional conclusion (like this one, I suppose) has now announced it to a large group, in a print medium that is hard to back away from later. It takes more mental effort to change your opinion on a widely disseminated, print statement than it does to just not repeat that verbal opinion you said to a couple people.

So, if the problem is that "if an individual learner never changes their mind based on new evidence, their chosen option could spread throughout the social network", then discussing in small groups in a format which leaves no record afterwards (at least until later stages of the decision) might help to avoid this problem. Maybe?