4chan is brighter than it lets on. But recently it's become a parody of itself. What once began hilarious and meme-laden has become a bunch of people repeating memes, which aren't funny unless they're clever.
I honestly think that 4chan has some of the highest comment standards of any board I can think of, particularly for initial posts (comments can be fairly vacuous). A lot of people go to /b for the trolling, and a lot of trolls go completely ignored or get called out almost immediately.
Sure the board isn't first-order intelligent, but intelligence (along with timing and a certain type of wit) certainly helps when trying to get people riled up.
Sure, there's a population bias. But Reddit used to have mostly intelligent comments. Not anymore.