I think you make a good point with the persistent karma score. Basically, Reddit is a site that has gamified popularity to the point where everyone is trying to make the quick, easy joke or reference as quickly as possible to score the highest number of points. The existence of sites to track the highest karma accounts only served to reinforce that behavior, which wound up having a bunch of knock-on effects like gimmick accounts that jammed themselves anywhere no matter how appropriate (which led to groupies that would try catching collateral karma), bots copying higher-scoring comments to try building a "trusted" account to then flip and sell to advertisers, and likely a bunch of other stuff that I'm not considering. In the end, there was a lot of shouting into the void and not much actual conversation. That's how it felt to me outside of smaller subreddit, at least.