I never understand why the most insightful comments about the topic at hand, the one that actually sheds some light on the topic by someone who might know a little about it, is always at the bottom of a thread on /.
Democracy is about popular opinions, not correct ones.
Socializing is about popular opinions and flattery, not reality.
Product sales are about trends, not technical best solutions.
Everywhere we humans go, it's quantity over quality. That's because of how we choose. We pick what lots of people want to believe is true, not what is true.
In defense of Slashdot, it's better here than most places, including off the net. About 5% of the posters here are insightful and will actually consider an opinion other than what their TV says, or friends in the local watering hole think is important.
If anything, it's the fanboys that make it difficult here. Apple, Ron Paul, Google, Obama, gays, Open Office, AR-15s, etc. They form little organized voting blocs who try to destroy any opinion that isn't fawning like their own on their topic of choice.