It's difficult to find good subreddits. Even if the subject matter of the subreddit interests you, it possibly only has dozen subscribers and received its last submission months ago. So subreddits are better than nothing, but could be better.

As an aside, I have found browsing reddit.com/r/all has allowed me to discover several neat subreddits I otherwise would have never found. (Warning, /r/all is all subreddits, including NSFW ones)