I put the problem down to incredibly inconsistent moderating.
Go to the rules page and you'll quickly see about half the rules are either entirely unenforced or completely out of date. That already sets a bad precedent for the large running of site, but it only gets worse when your entire community is moderated by unpaid, apathetic volunteers who more or less enforce the rules only when they feel like it.
You'll get things like a thread explicitly about how black people are criminals on /tv/ stay up for a whole day, but then a thread asking for book recommendations for books based on movies will be deleted in an instant.
There's no rhyme or reason to the moderation, no transparency, and no actual motivation to post quality threads (or perhaps more accurately, no reason to avoid posting horrible threads) if the moderators are so horrible at their work.
Honestly, maybe this is just cognitive bias, but I feel like the problem wasn't as bad under moot. Yeah, moot had his own issues, but he at least seemed to realise the boards needed clear visions if they were to be successful. Ever since the gook took over, everything feels way more apathetic. It's like the episode of the Simpsons where Ned Flanders becomes principle of the school; all the pent-up insanity just gets unleashed and he's powerless to stop any of it.