The stabilizer benefits communities because people in those Hive-platform communities want to hold value or make payments in a token that doesn't fluctuate wildly in price according to speculative markets. HBD provides this service within the Hive community and the stabilizer facilitates its function while also earning a profit from price fluctuations. The profit is then returned to the DHF where it can be used to fund projects (even if it isn't used to fund projects, it still benefits the Hive community by reducing the number of coins in circulation, which would tend to increase their price).