Incentives. Stacker.news attaches incentives to encourage behavior that is valued by the people that use stacker.news. By using bitcoin as the medium of exchange (something with real value) the site and we the users can encourage and discourage behavior. Quality is rewarded. Spam is discouraged. The longer I am a part of this site the more obvious it is to me that this is the way for web sites to handle many of their problems. Bitcoin fixes yet another problem.