There's also the flip side: when everyone can say something, they do, and we get a ton of cat pictures and other... less intellectually stimulating material. Or more pungently: Opinions are like ----, everyone's got one, and they don't always smell good.

There's some level of value in having some barrier to competition, it discourages the apathetic and very casual participant and encourages a higher signal:noise ratio in the discussion discussion.

Well, at least in my opinion. :)