On Reddit, it seems like there are two types of subreddits: community and dropbox. In a community-type subreddit, people actively upvote, comment, and discuss. In a dropbox subreddit, nobody cares what you shared because everyone comes here to share their own content. So there are no upvotes or comments, even if the subreddit has hundreds of thousands of people.
For example: /freebsd is a community,
But /indieGaming is a drop box (unfortunately)