The answer appears to be “Yes”–at least according to one creatively-designed research study.
For the study, New York University’s Pablo Barbera examined millions of social media users in Spain, Germany, and the US. He found that “most social media users are embedded in ideologically diverse networks, and that exposure to political diversity has a positive effect on political moderation.” The finding held up even when compared to survey findings and voting behavior data.
However one judges Barbera’s study, it is certainly heartening that there is at least some evidence both of the moderating power of diversity and of social media’s capacity to marshal it.
Now the challenge will be to enhance both.