The problem is that most modern algorithms tend to recommend most stuff that you engage in, so if you continuously comment against conservative viewpoints, you are doing to get more conservative stuff in your feed.
Hackernews is by far the best because it tends to self govern with downvoting/flagging baseless comments. People definitely have a bias, but you can post disagreement on things and actually have good discussion, whereas on Reddit you basically just get downvoted and people just tell you are wrong without any sort of justification.