A little experimentation has shown me that the word "money" puts an uneasy frame of reference around what we do here. People immediate start thinking about "scams" and "cheating" and negative stuff. Saying "reward"-- because it's a very open-ended idea-- leaves things very open. 10+ years ago, a lot of us were blogging on Xanga and other places... it was "social blogging" like this, and we were "rewarded" with something called "e-props" which were essentially useless tokens, except in the web site's own store. But because they weren't "money," nobody ever even considered the word "scam;" it was cool to get rewarded, even if it translated to nothing at all.

Your assessment is precisely correct. And it has little to do with finances... and more to do with the content's ability to drive growth. Just like you probably wouldn't keep shopping at a grocery that had half rotten fruit and broken boxes of cereal, new creators of authentic content won't sign up to be part of a venue that's an ocean of spam and crap... so the site would slowly atrophy and die.