I've found something similar with reddit. Posting in a niche subreddit might look like a nonstarter with many posts only receiving a couple upvotes and 0-2 comments, but the actual site visits seem to be a couple hundred times the upvote count (at least for me).

It makes sense to me, in that small subs see something like a trickle of content, and subscribers tend to be pretty into the topic to have sought the specific community out. So you could get a much higher % of the subreddit's total population visiting your site, even if they don't bother to actually upvote it.