Comment by thinkingtoilet

As others have pointed out, the answer is moderation. High quality, diligent moderation. Reddit is the ultimate proof of this. A highly moderated, focused subreddit can be a wonderful place. A loosely moderated subreddit quickly devolves into memes and lowest common denominator posts, which is totally fine for specific subjects, or even meme-based subreddits for a given topic. If you want quality, you have to invest in it. It doesn't just happen. The good news is that it's self reinforcing. Once you have something good, people start policing themselves and others. This can go overboard of course, but it can be a good a really good thing. I often see comments here along the lines of, "comments like this are not welcome here".