As long as the transaction can be concluded, it means that many parties and the empty side are equal. Futures is a two-way transaction. If you sell 1, you must buy 1. If you only sell and don't buy, then you can't make a deal, such as stopping the board.

There are two kinds of buying and selling, one is to open a position, and the other is to close a position and leave. For example, in your question, shorting refers to actively shorting in the market, but what he hedges may not necessarily come from actively buying in the market, but may correspond to buying and closing positions in the market.

Moreover, shorting can't be completely active in opening positions, and many of them may be empty positions left by many parties. So it is not always understandable to do more. I'm buying a stock index, and I think I'll buy it up. There are many more, and what I sold in the early stage is being repurchased.