People will always bring up "politics" in relation to when the website began to sink in quality, but for me it was a issue that I feel like seeded for all that to happen.
2011-2012 was when the wind really began to change direction on that website. Overnight it felt like all the big boards were obsessed with Reddit/Tumblr, being Anti-Reddit/Tumblr, and making sure they had "board culture". Which was always there, but rather than being a unspoken joke between strangers, it felt forced. Didn't like this shitty forced meme? Well you're a REDDITOR! That's really when I feel like most major boards began to shift downward. Still plenty of gold left in the hills in the upcoming years, but I felt like that was kinda the beginning of the end.