Karma is the arbitrary currency that reddit users can give to one another. Every user has an unlimited supply of karma, but only if they give it away one unit at a time on a per-post basis. I’m not an economist, but that sounds like the start of an inflation problem.

Because having higher karma is desired, users behave in ways that will get them karma (karma-whoring). Similarly, users who do not agree with the fat part of the bell curve are punished by losing karma. Posts with low karma are sorted to the bottom and are less-read and set out from the chorus.

It follows that the way to get the most karma is to say stuff that most people will agree with, that is, to be average.

It’s therefore in the interests of reddit users to be as agreeable and indistinguishable as possible from the average voice, giving us the hive-mind of tedium and mediocrity that we see.

It’s also worth noting that there’s a massive selection bias inherent in participating in a web community that calls itself “the frontpage of the internet,” so this pressure to conform is applied an already pretty homogenous mixture of people. It’s a bit chicken and egg, but the result is bad photoshops either way.

Edit: A bit more. Doing some armchair economic analysis on this.

While massive inflation is probably a problem, the fact that nothing is being bought with this currency probably takes a big part of the downside off the table, it’s not like the goods that people would buy with their karma are getting more expensive, because there are no goods.

It’s the signaling that’s messed up. In normal money economies, money acts as a production signal. When money is paid for a good, if the price is “too high” the price acts as a signal to produce more of that good. If you’re selling something and people will spend whatever price you set, you’re clearly going to want to make more–and anyone who witnesses this will want to get in and get a piece of the action. The result is that the price is bid down.

Karma however is not scarce, therefore people will give it away readily–there’s no downside to doing so. This means that posts/users who would not have been good enough to get karma if karma was scarce will be given some, resulting in an “overproduction” of that type of post. There’s therefore an overproduction of the type of average posts, and an incentive to make average posts in order to get more karma.