It may not work. It's still too early to tell. If you look at other content sites that have tried to pay out to contributors (think Mahalo), their models didn't work either. Huffington post finds more success by paying nothing.
I think the problem here is that the introduction of payment changes the psychology from one of sharing information to one of maximizing income (gift Vs capital). In the latter mode of operation the quality of the information is a secondary concern.
I had similar misgivings/feelings while using the product. However: Two observations: 1.) they did include user-selected charities lately in their distribution of "upvote" profits; 2.) The point is less about making money, more about adverse selection (keeping out trolls). Nobody could subsist off of this in any real kind of way. If they did--the value they would have to provide would be immense.
Hopefully the small amounts we are dealing with makes it less worthwhile for spammers as well as not seem like a purely profit driven incentive. All things in moderation as they say.
The difference is their money comes from ad revenue not from the users themselves. Didnt huffington post sell for quite a lot of money to AOL and the people who actually built it got nothing ?