we can argue about the benefits of short selling until we are blue in the face. given a long time horizon I might agree that short selling doesnt add a huge amount to the market. but given a long time horizon, the market doesn't add happiness or well-being to the planet or it's denizens. the issue at hand is there are hundreds of funds with trillions of dollars at their disposal - changing the rules of this magnitude is like a big ocean wave hitting a river canoe - it will teeter - it will rock back and forth, and its a coin flip whether if will capsize.