Well here's an interesting observation: the "right" subreddit cites some sources that the "left" subreddit cites, but not vice versa. For example, NYT and Politico appear near the tail of the "right" sub's sources and near the head of the "left" sub's sources, but none of the "right" sub's sources appear anywhere in the "left" sub's sources.
So, assuming that NYT and Politico are left-leaning, it would appear that the "right" sub links to its opponents' views, while the "left" sub does not.
So, assuming that NYT and Politico are left-leaning, it would appear that the "right" sub links to its opponents' views, while the "left" sub does not.
The implications of this are left to the reader.