I've noticed an increase in upvote/downvotes based on whether or not a person agrees, rather than whether the comment was on-topic and contributed to the conversation.

I try to make a point of upvoting comments I disagree with, but that are clearly made in good faith in order to counteract this trend.

I suppose this problem is a normal low entropy state in community moderated systems.

It takes a lot more mental energy to moderate based on the value of the conversation rather than whether you personally agree.