The identical threads thing is definitely fueling that. If a user comes to the subreddit a sees a thread about something that’s against their political ideology, they may still jump in and debate depending how much they like to argue.

But if they come to the subreddit and see ten identical threads about that same subject or news story, they’re going to be way less likely to jump in and discuss. Nobody likes debating in an echo chamber.

If something isn’t done about the identical crosspost spam, it’s going to tilt the subreddit politically until there is no actual debate and it’s just another r/politics or r/conservative clone (although honestly I think we all know which one it’s going to be).