I think the "post by post" method of valuation will never work, it will depend on track record and consistency, the way it does with everything. You probably buy brands you trust in clothes, watch movies with actors you already like - track record. The random votes for random accounts are essentially rolling the dice in the hope that they can do it again or will add some value. The "worth" of any single post is not a very good measure of anything really and what that person does with their reward is up to them, but that is also going to affect others.