I've been using Reddit since around mid-2009 (pre-Digg exodus). In my honest opinion, the signs of decline on Reddit have been bubbling for a while, and that's forgoing any consideration of operational/executive decisions that have been made along the way.

Don't get me wrong, Reddit even in 2009 wasn't a consistent bastion of quality, productive, insightful discussion, and a good amount of posts on the frontpage on a given day were memes (not to say those are inherently "bad" posts; peak f7u12 anyone?). But the discussions that were had were, for the most part, friendly and/or constructive in some meaningful way. Over the years though, as the userbase grew and the site became increasingly "mainstream," I noticed there was an uptick of either one or both of two things: 1) low effort posts/comments and 2) sheer vitriol in discussions.

When you combine those two things, you get what -- in my opinion -- is a social media platform with high levels of "engagement" that VCs/execs love to tout and leverage (see Reddit's recent IPO ambitions), but ultimately, a platform that's merely a shell of what it once used to be.

As that happened, I found myself using Reddit less as a "fun" social media platform and more as a tool -- using it for discussions and/or information about niche hobbies, interests, news topics, etc. While the dominance of forums in that area may have been overtaken by subreddits over the years, I don't think there was anything particularly unique about what Reddit as a platform was doing to help these sort of communities exist, and I really doubt that Reddit will be the last place these communities can thrive.