Not to mention the massive bias.
If it's anti-rich people, pro-gay, pro-drugs, anti-corporation, anti-government, anti-religion, anti-foxnews, socialist etc etc then it'll get upvoted endlessly.
The worrying thing is that people who constantly moan about how misinformed and biased fox news viewers are, are on a website with a ridiculous bias, which also often carries untrue stories because they fit the agenda.
There's a reason why news sites are still very very popular. We need editors. If you allow people to upvote what they want, you end up with complete rubbish and endless circlejerking. The front page is often (When you remove the funny pictures) lots of "We all obviously agree with this. Who agrees with me?!!"